Nanoparticles for use in light emitting applications

Abstract

Resins comprising nanoparticles formed from π-conjugated cross-linked polymers are disclosed, together with their methods of manufacture and their applications in light emitting devices.

Claims

1. A resin suitable for use in the fabrication of a light emitting device, the resin comprising a plurality of nanoparticles dispersed in an encapsulation medium, wherein the nanoparticles are photoluminescent conjugated polymer nanoparticles formed from a π-conjugated cross-linked polymer, the π-conjugated cross-linked polymer comprising a) 80-99.9 mol. % of π-conjugated monomers, and b) 3-10 mol. % of a cross-linker having the formula I shown below: ##STR00068## wherein Z.sub.1 and Z.sub.2 are monomeric moieties, and Y is absent, a bond, or a linking group, wherein the encapsulation medium is a transparent polymeric encapsulation medium.

2. A resin according to claim 1, wherein the cross-linker of formula I is π-conjugated.

3. A resin according to claim 1, wherein the cross-linker has the formula II shown below: ##STR00069## wherein Y is absent, a bond, or a linking group.

4. A resin according to claim 1, wherein the cross linker has the formula III shown below: ##STR00070## or wherein the cross-linker has the following structure: ##STR00071##

5. A resin according to claim 1, wherein one or more of the π-conjugated monomers comprise a moiety having the formula IV shown below: ##STR00072## wherein R.sub.1 and R.sub.2 are each independently hydrogen or a group:
—X-Q wherein X is absent selected from the group consisting of (1-30C)alkylene, —O-(1-30C)alkylene, —S-(1-30C)alkylene, —NH-(1-30C)alkylene, —N-[(1-30C)alkylene], (2-30C)alkenylene, (2-30C)alkynylene, —[(CH.sub.2).sub.2—O].sub.n—, —[O—(CH.sub.2).sub.2].sub.n— —[O—CH.sub.2MeCH.sub.2].sub.n—, —[CH.sub.2MeCH.sub.2—O].sub.n— and —[O—Si(R.sub.z).sub.2].sub.n (wherein R.sub.z is (1-4C)alkyl and n is 1 to 30), —[(CH.sub.2).sub.n′—(CF.sub.2).sub.m′]— (wherein n′ is 0-20 and m′ is 1 to 30) and Q is a terminal group selected from hydrogen, halogen, methyl, hydroxyl, carboxy, (1-4C)alkoxycarbonyl, amino, —C═CH.sub.2, —C≡CH, —SH, —CF.sub.3, OSO.sub.3H, —SO.sub.3H, —OPO.sub.2OH and zwitterions (e.g. betaine), and a polymerisable group selected from acrylates, epoxy and styrene, or a salt thereof, or R.sub.1 and R.sub.2 are aryl or heteroaryl groups optionally substituted with a substituent group; or R.sub.1 and R.sub.2 are linked so that, together with the carbon atom to which they are attached, they form ring system optionally substituted with a substituent group.

6. A resin according to claim 1, wherein the plurality of nanoparticles are configured to emit visible light of a single wavelength in the visible spectrum (e.g. red, green, blue, or yellow light); or wherein each nanoparticle emits light of a single wavelength in the visible spectrum.

7. A resin according to claim 1, wherein the plurality of nanoparticles are configured to emit visible light of two or more wavelengths in the visible spectrum (e.g. red, green, blue, and/or yellow light or a range of wavelengths that collectively form white light); or wherein at least one nanoparticle can emit more than one wavelength of light in the visible spectrum (e.g., red and green or red, green and blue).

8. A resin according to claim 7, wherein a first population of the nanoparticles emit light at a first wavelength in the visible spectrum (e.g. red light) and a second population of nanoparticles emit light at a second wavelength in the visible spectrum (e.g. green light) and optionally a third population of nanoparticles emit light of third wavelength in the visible spectrum (e.g. blue light).

9. A resin according to claim 1, wherein the nanoparticles have a particle size (Z-average, measured by DLS) of 20-400 nm, or 30-300 nm.

10. A resin according to claim 1, wherein the nanoparticles have a degree of polymerisation of 10 to 800.

11. A resin according to claim 1, wherein the encapsulation medium is selected from siloxane-based media and/or acrylate polymers.

12. A resin according to claim 1, wherein the loading of nanoparticles within the resin is 0.005 to 5 wt. %.

13. A light emitting device comprising a resin as defined in claim 1 and a primary light source configured to illuminate the resin.

14. A light emitting device according to claim 13, wherein the primary light source emits UV and/or blue light; and/or wherein the nanoparticles in the resin emit secondary light.

15. A light emitting device according to claim 13, wherein the primary light is absorbed by the resin and the only light emitted from the device is secondary light.

16. A light emitting device according to claim 15, wherein the secondary light is white light.

17. A light emitting device according to claim 15, wherein the nanoparticles either (i) emit a mixture of red, green and blue light (which collectively forms the perception of white light), a mixture of blue and yellow light (which collectively forms the perception of white light), yellow and green light or the nanoparticles may emit white light (i.e. a broad spectrum of visible light wavelengths, which collectively form the perception of white light).

18. A light emitting device according to claim 13, wherein a proportion of the primary light transmits through the resin and the light emitted from the device is a mixture of primary light and secondary light.

19. A light emitting device according to claim 18, wherein the device emits white light; and/or wherein the primary light is blue light and the secondary light is selected from either yellow light, red and green light or a range of wavelengths of visible light that, together with the primary blue light transmitted through the resin, create white light.

20. A method of forming a resin according to claim 1, the method comprising the steps of: (i) dispersing the nanoparticles according to claim 1 within a precursor encapsulation medium; and either (ii) curing the precursor encapsulation medium to form the encapsulation medium; or (iii) injection moulding and/or extruding the precursor encapsulation medium to form the resin.

Description

EXAMPLES

(1) Examples of the invention will now be described, for the purpose of reference and illustration only, with reference to the accompanying figures, in which:

(2) FIG. 1 shows DLS particle size histograms of the cross-linked nanoparticles of Example 1 in water (solid line) or THF (broken line).

(3) FIG. 2 shows UV/Vis spectra of the cross-linked nanoparticles of Example 1 in water (solid line) or THF (broken line).

(4) FIG. 3 shows PL spectra of the cross-linked nanoparticles of Example 1 in water (solid line) or THF (broken line).

(5) FIG. 4 shows normalised absorption and emission spectra (λ.sub.exc=390 nm) of CL-PFO, CL-PFO-BT and CL-DBT.sub.h CPNs in water [Example 7].

(6) FIG. 5 shows normalised absorption and emission spectra (λ.sub.exc=390 nm) of CL-PFO, CL-PFO-BT and CL-DBT.sub.h CPNs in THF [Example 7].

(7) FIG. 6 shows emission profile of mixture of cross-linked RGB CPNs at different ratios [Example 7].

(8) FIG. 7. Acrylic films containing cross-linked RGB CPNs (Films A-D) under ambient light (top) and under UV illumination (bottom) [Example 7].

(9) FIG. 8 shows emission spectra generated by Film A by down-conversion of UV-light at λ.sub.exc=381 nm (left) and λ.sub.exc=393 nm (right) [Example 7].

(10) FIG. 9 shows emission spectra generated by Film B by down-conversion of UV-light at λ.sub.exc=381 nm (left) and λ.sub.exc=393 nm (right) [Example 7].

(11) FIG. 10 shows emission spectra generated by Film C by down-conversion of UV-light at λ.sub.exc=381 nm (left) and λ.sub.exc=393 nm (right) [Example 7].

(12) FIG. 11 shows emission spectra generated by Film D by down-conversion of UV-light at λ.sub.exc=381 nm (left) and λ.sub.exc=393 nm (right) [Example 7].

(13) FIG. 12 shows position in the CIE 1931 chromaticity diagram of light emitted by Films A-D when irradiated in a remote phosphor LED array at λ.sub.exc=381 nm [Example 7].

(14) FIG. 13 shows position in the CIE 1931 chromaticity diagram of light emitted by Films A-D when irradiated in a remote phosphor LED array at λ.sub.exc=393 nm [Example 7].

(15) FIG. 14 shows normalised absorption and emission spectra (λ.sub.exc=390 nm) of cross-linked white CPNs base on PFO in THF [Example 8].

(16) FIG. 15 shows silicone based films containing cross-linked RGB CPNs at 0.05 and 0.1 wt. % under ambient light (left) and under UV illumination (right) [Example 8].

(17) FIG. 16 shows emission spectra generated by Film E by down-conversion of UV-light at λ.sub.exc=381 nm (left) and λ.sub.exc=393 nm (right) [Example 8].

(18) FIG. 17 shows emission spectra generated by Film F by down-conversion of UV-light at λ.sub.exc=381 nm (left) and λ.sub.exc=393 nm (right) [Example 8].

(19) FIG. 18 shows position in the CIE 1931 chromaticity diagram of light emitted by Films E-F when irradiated in a remote phosphor LED array at λ.sub.exc=381 nm [Example 8].

(20) FIG. 19 shows normalised absorption & emission spectra (λ.sub.exc=390 nm) of Examples 9-11 in water.

(21) FIG. 20 shows silicone-based films (Film G) containing cross-linked green (Example 2) under ambient light (left) and under UV illumination (right) [Example 20].

(22) FIG. 21 shows the Emission spectra generated by Film G by down-conversion of UV-light λ.sub.exc=385 nm [Example 20].

(23) FIG. 22 shows the Emission spectra generated by Film J (left) and Film K (right) by down-conversion of UV-light at λ.sub.exc=385 nm [Example 20].

(24) FIG. 23 shows the position in the CIE 1931 chromaticity diagram of light emitted by Film J and Film K when irradiated in a remote phosphor LED array at λ.sub.exc=385 nm [Example 20].

(25) FIG. 24 shows the Emission spectra generated by Film L (top, left), Film M (top, right) and Film N (bottom) by down-conversion of blue light at λ.sub.exc=450 nm [Example 20].

(26) FIG. 25 shows the position in the CIE 1931 chromaticity diagram of light emitted by Films L-N when irradiated in a remote phosphor LED array at λ.sub.exc=450 nm [Example 20].

(27) FIG. 26 shows the Emission spectra generated by Film O (top, left), Film P (top, right) and Film Q (bottom) by down-conversion of UV-light at λ.sub.exc=385 nm (Example 21).

(28) FIG. 27 shows the Emission spectra generated by Film O (top, left), Film P (top, right) and Film Q (bottom) by down-conversion of blue light at λ.sub.exc=450 nm (Example 21).

(29) FIG. 28 shows the position in the CIE 1931 chromaticity diagram of light emitted by Films O-Q when irradiated in a remote phosphor LED array at λ.sub.exc=450 nm (Example 21).

(30) FIG. 29 shows a schematic representation of an exemplary light emitting device according to an aspect of the present invention. The light emitting device (2) shown in FIG. 29 is a conventional “remote phosphor” LED assembly with a standard LED chip (3). Above the LED chip (3) is a LED well (4) which optionally comprises a volume of a commercially available resin (5) that covers and submerges the LED chip (3). A remote phosphor (6) of sufficient thickness and formed from the resin of the present invention is positioned at the opening of the well (4). The remote phosphor (6) may be formed by curing a precursor mixture which comprises the nanoparticles of the present invention and any other required reactants, e.g. by exposure to light, to form the resin layer of the remote phosphor (6) or it may be prefabricated by, for example, extrusion of nanoparticles of the present invention in the presence of an encapsulation medium to form the remote phosphor (6).

(31) FIG. 30 shows a schematic representation of an exemplary light emitting device according to an aspect of the present invention. The light emitting device shown in FIG. 30 is a conventional “potted phosphor” LED assembly (2) with a standard LED chip (3). Above the LED chip (3) is a LED well (4) that optionally comprises a volume of a commercially available resin (5) that covers and submerges the LED chip (3), and a potted phosphor layer (6) present within the well (4). The potted phosphor layer (6) is formed from the resin of the present invention. The potted phosphor layer (6) may be formed by curing a precursor mixture which comprises the nanoparticles of the present invention and any other required reactants, e.g. by exposure to light, to form the resin layer of the potted phosphor (6) or it may be prefabricated by, for example, extrusion of nanoparticles of the present invention in the presence of an encapsulation medium to form the potted phosphor (6).

(32) FIG. 31 shows a schematic representation of an exemplary light emitting device according to an aspect of the present invention. The light emitting device shown in FIG. 31 is an “on chip” LED assembly (2) with a standard LED chip (3). Above the LED chip (3) is a LED well (4) that optionally comprises a volume of a commercially available resin (5) that covers and submerges the LED chip (3) that has a phosphor layer (6) present on the chip (3). The phosphor layer (6) may be formed by depositing phosphor or the phosphor in a precursor mixture on the chip (3) which optionally comprises other required reactants to form the resin layer or it may be prefabricated by, for example, extrusion of nanoparticles of the present invention in the presence of an encapsulation medium to form the “on chip” phosphor layer (6).

Example 1—Cross-Linked PFO Nanoparticles (which are UV Absorbing and Emit Blue Light)

(33) Synthesis

(34) Referring to Scheme 1 and Table 1 shown below, sodium dodecyl sulfate (SDS) (50.0 mg) and deionised water (10 mL) were transferred to a Schlenk tube and the resultant solution was degassed by bubbling with argon for 20 minutes. Monomer A (see Table 1), crosslinker B (see Table 1) and monomer C (58.6 mg, 9.12×10.sup.2 mmol) were dissolved in toluene (1 mL), to which hexadecane (78 μL) was also added, and this solution was degassed for 5 minutes in the same manner. Tetrakis(triphenylphosphine)palladium(0) (2.2 mg, 9.13×10.sup.4 mmol) was added to the monomer solution, which was then transferred to the reaction vessel. The reaction mixture was emulsified by ultrasonication (Cole Parmer 750 W ultasonicator, fitted with microtip, on 22% power) for 2 minutes while cooling with an ice bath. The Schlenk tube was resealed and the miniemulsion was heated to 72° C., followed by addition of 1M aqueous sodium hydroxide solution (365 μL), and the reaction mixture was stirred for 16 hours. After cooling to room temperature, the cap of the reaction vessel was removed and the emulsion was stirred for 5 hours to remove the residual toluene.

(35) ##STR00047##

(36) TABLE-US-00001 TABLE 1 Reaction variables for synthesis of cross-linked PFO nanoparticles Monomer A Crosslinker B Sample Name (mass, moles) (mass, moles) NP-X2.5 45.0 mg  2.9 mg 8.21 × 10.sup.−2 mmol  4.6 × 10.sup.−3 mmol NP-X5 40.0 mg  5.8 mg 7.29 × 10.sup.−2 mmol  9.1 × 10.sup.−3 mmol NP-X10 30.0 mg 11.6 mg 5.47 × 10.sup.−2 mmol 1.82 × 10.sup.−2 mmol
Surfactant Removal and DLS Analysis (Nanoparticles in Water)

(37) A 400 μL aliquot of the crude nanoparticle suspension was diluted with 1.6 mL of deionised water, to which Amberlite XAD-2 resin (20 mg, pre-washed with 2×2 mL of water) was added. The suspension was shaken at room temperature for 15 minutes before decanting off the nanoparticle suspension. This Amberlite XAD-2 purification step was repeated, after which time the suspension no longer foamed upon shaking and was filtered through glass wool prior to dynamic light scattering (DLS) analysis of particle size using a Malvern Zetasizer Nano ZS. Results are shown in Table 2 and FIG. 1.

(38) TABLE-US-00002 TABLE 2 DLS analysis of cross-linked PFO nanoparticles in water Z- Size by St. Sample Average Intensity Dev. Name (d. nm) (d. nm) (nm) Pdl NP-X2.5 128 154 69 0.16 NP-X5 130 151 60 0.14 NP-X10 129 150 56 0.13
DLS Analysis (Nanoparticles in THF)

(39) A 200 μL aliquot of the crude nanoparticle suspension was flocculated through addition of 1.3 mL toluene and the polymer was isolated by centrifugation (14,000 rpm, 1 minute) and decantation of the supernatant. The polymer was dried in air to remove residual methanol before dissolving in tetrahydrofuran (THF, 1 mL). The resultant suspension was measured directly using a Malvern Zetasizer Nano ZS. Results are shown in Table 3 and FIG. 1.

(40) TABLE-US-00003 TABLE 3 DLS analysis of cross-linked PFO nanoparticles in THF Sample Z-Average Size by Intensity St. Dev. name (d. nm) (d. nm) (nm) Pdl NP-X2.5 — — — n/a.sup.[a] NP-X5 174   98 (99.6%) 74 (99.6%) 0.13 4827 (0.4%) 711 (0.4%).sup.[a] NP-X10 147 175 73 0.15 .sup.[a]secondary peak likely to result from a small proportion of aggregated nanoparticles
UV/Vis Analysis (Nanoparticles in Water or THF)

(41) Following surfactant removal via treatment with Amberlite XAD-2, 40 μL of the nanoparticle suspension was diluted with 3 mL of water. UV-Vis absorption spectra of the nanoparticles at this concentration were recorded on a Varian Cary 555000UV-Vis-NIR spectrophotometer at room temperature. FIG. 2 shows UV/Vis spectra of the cross-linked PFO nanoparticles.

(42) Photoluminescence (PL) Analysis (Nanoparticles in Water or THF)

(43) Following surfactant removal via treatment with amberlite XAD-2, 40 μL of the nanoparticle suspension was diluted with 3 mL of water. PL spectra were recorded on a Varian Cary Eclipse fluorimeter. FIG. 3 shows PL spectra of the cross-linked PFO nanoparticles

(44) Photoluminescence (PL) Analysis (Nanoparticles in Water)

(45) Photoluminescence measurements were obtained using a Fluoromax-4 spectrofluorometer. Measurements were carried out on dilute dispersions of the nanoparticles in water (800 μL, abs>1), using the same volume of water for background measurements. The results are provided in Table 4.

(46) TABLE-US-00004 TABLE 4 Optical properties of PFO nanoparticles in water Sample Name λ.sub.max λ.sub.em.sup.[a] NP-X2.5 390 440 NP-X5 390 438 NP-X10 390 437 [a]λ.sub.ex = 380 nm

Example 2—5% 2,1,3-Benzothiadiazole, 35% 9,9-Di(undecanoic acid)fluorene and 5% 9,9′-Spirobifluorene Cross-Linked Polyfluorene Nanoparticles (which are UV Absorbing and Emit Green Light)

(47) Synthesis

(48) ##STR00048##

(49) In a Schlenk tube was added water (22.0 mL), sodium dodecyl sulfate (110 mg, 382 μmol) and 1M aqueous sodium hydroxide (1080 μL, 1080 μmol). The solution was purged with argon for 2 hours. In a vial was weighed 9,9-dioctylfluorene-2,7-diboronic acid bis(1,3-propanediol) ester (111.7 mg, 200 μmol), 2,7-dibromo-9,9-di(undecanoic acid)fluorene (96.9 mg, 140 μmol), 2,2′,7,7′-tetrabromo-9,9′-spirobifluorene (12.6 mg, 20 μmol), 4,7-dibromobenzo[c]-1,2,5-thiadiazole (5.9 mg, 20 μmol) tris(dibenzylideneacetone)dipalladium(0) (4.6 mg, 5 μmol), tri(o-tolyl)phosphine (9.1 mg, 30 μmol) and hexadecane (171 μL, 585 μmol). The vial was transferred to an argon filled glovebox, sealed with a rubber septum and removed. Toluene (2.19 mL) was added to the vial and the suspension sonicated until a homogenous solution was achieved. The initial aqueous solution was cooled to 0° C. in an ice bath, the ultrasonic probe inserted and the toluene solution injected rapidly into the water. The solution was ultrasonicated for 1 minute, stirred for 30 seconds and ultrasonicated for 1 further minute. The Schlenk tube was sealed, placed in a preheated oil bath at 50° C. and stirred for 20 hours. The Schlenk was opened and a stream of nitrogen gas passed over the emulsion at 50° C., with stirring. The emulsion was cooled to room temperature, the volume increased to 23.0 mL with deionised water and filtered through a glass wool plug. The emulsion was obtained as a milky dark green solution. DLS (water): Z-average=79.0 nm, Pdl=0.117, D.sub.n=52.4 nm and SD=15.3 nm. UV-Vis Abs. (water): λ.sub.max=380 nm, λ.sub.sec.=450 nm, λ.sub.onset=520 nm. UV-Vis PL (water): λ.sub.max=535 nm, λ.sub.sec.=424 nm.

Example 3—5% 4,7-Bis(4-hexylthiophen-2-yl)benzo[c][1,2,5]thiadiazole and 5% 9,9′-Spirobifluorene Cross-Linked Polyfluorene Nanoparticles (which are UV Absorbing and Emit Red Light)

(50) Synthesis

(51) ##STR00049##

(52) In a Schlenk tube was added water (22.0 mL), sodium dodecyl sulfate (110 mg, 382 μmol) and 1M aqueous sodium hydroxide (800 μL, 800 μmol). The solution was purged with argon for 2 hours. In a vial was weighed 9,9-dioctylfluorene-2,7-diboronic acid bis(1,3-propanediol) ester (111.7 mg, 200 μmol), 9,9-dioctyl-2,7-dibromofluorene (76.8 mg, 140 μmol), 2,2′,7,7′-tetrabromo-9,9′-spirobifluorene (12.6 mg, 20 μmol), 4,7-bis(5-bromo-4-hexyl-2-thienyl)-2,1,3-benzothiadiazole (12.5 mg, 20 μmol), tris(dibenzylideneacetone)dipalladium(0) (4.6 mg, 5 μmol), tri(o-tolyl)phosphine (9.1 mg, 30 μmol) and hexadecane (171 μL, 585 μmol). The vial was transferred to an argon filled glovebox, sealed with a rubber septum and removed. Toluene (2.19 mL) was added to the vial and the suspension sonicated until a homogenous solution was achieved. The initial aqueous solution was cooled to 0° C. in an ice bath, the ultrasonic probe inserted and the toluene solution injected rapidly into the water. The solution was ultrasonicated for 1 minute, stirred for 30 seconds and ultrasonicated for 1 further minute. The Schlenk tube was sealed, placed in a preheated oil bath at 50° C. and stirred for 20 hours. The Schlenk was opened and a stream of nitrogen gas passed over the emulsion at 50° C., with stirring. The emulsion was cooled to room temperature, the volume increased to 23.0 mL with deionised water and filtered through a glass wool plug. The emulsion was obtained as a milky bright red solution. DLS (water): Z-average=105 nm, Pdl=0.125, D.sub.n=64.4 nm and SD=20.8 nm. UV-Vis Abs. (water): λ.sub.max=382 nm, λ.sub.sec.=433 nm, λ.sub.sec.=514 nm, λ.sub.onset=620 nm. UV-Vis PL (water): λ.sub.max=621 nm, λ.sub.sec.=437 nm.

Example 4—10% 4,7-Bis(4-hexylthiophen-2-yl)benzo[c][1,2,5]thiadiazole and 5% 9,9′-Spirobifluorene Cross-Linked Polyfluorene Nanoparticles (which are UV Absorbing and Emit Red Light)

(53) Synthesis

(54) ##STR00050##

(55) In a Schlenk tube was added water (22.0 mL), sodium dodecyl sulfate (110 mg, 382 μmol) and 1M aqueous sodium hydroxide (800 μL, 800 μmol). The solution was purged with argon for 2 hours. In a vial was weighed 9,9-dioctylfluorene-2,7-diboronic acid bis(1,3-propanediol) ester (111.7 mg, 200 μmol), 9,9-dioctyl-2,7-dibromofluorene (65.8 mg, 120 μmol), 2,2′,7,7′-tetrabromo-9,9′-spirobifluorene (12.6 mg, 20 μmol), (25.1 mg, 40 μmol), tris(dibenzylideneacetone) dipalladium(0) (4.6 mg, 5 μmol), tri(o-tolyl)phosphine (9.1 mg, 30 μmol) and hexadecane (171 μL, 585 μmol). The vial was transferred to an argon filled glovebox, sealed with a rubber septum and removed. Toluene (2.19 mL) was added to the vial and the suspension sonicated until a homogenous solution was achieved. The initial aqueous solution was cooled to 0° C. in an ice bath, the ultrasonic probe inserted and the toluene solution injected rapidly into the water. The solution was ultrasonicated for 1 minute, stirred for 30 seconds and ultrasonicated for 1 further minute. The Schlenk tube was sealed, placed in a preheated oil bath at 50° C. and stirred for 20 hours. The Schlenk was opened and a stream of nitrogen gas passed over the emulsion at 50° C., with stirring. The emulsion was cooled to room temperature, the volume increased to 23.0 mL with deionised water and filtered through a glass wool plug. The emulsion was obtained as a milky bright red solution. DLS (water): Z-average=130 nm, Pdl=0.264, D.sub.n=58.4 nm and SD=20.9 nm. UV-Vis Abs. (water): λ.sub.max=382 nm, λ.sub.sec.=432 nm, λ.sub.sec.=515 nm, λ.sub.onset=623 nm. UV-Vis PL (water): λ.sub.max=625 nm.

Example 5—2% 9,9-Di(undecanoic acid)fluorene, 5% 2,1,3-Benzothiadiazole, 33% Di(hex-5-en-1-yl)fluorene and 5% 9,9′-Spirobifluorene Cross-Linked Polyfluorene Nanoparticles (which are UV Absorbing, Emit Green Light and Possess a Pendent Terminal Double Bond to Participate in Polymerisation with a H—Si Functionalised Resin)

(56) Synthesis

(57) ##STR00051##

(58) In a Schlenk tube was added water (22.0 mL), sodium dodecyl sulfate (110 mg, 382 μmol) and 1M aqueous sodium hydroxide (816 μL, 816 μmol). The solution was purged with argon for 2 hours. In a vial was weighed 9,9-dioctylfluorene-2,7-diboronic acid bis(1,3-propanediol) ester (111.7 mg, 200 μmol), 2,7-dibromo-9,9-di(undecanoic acid)fluorene (5.5 mg, 8 μmol), 2,2′,7,7′-tetrabromo-9,9′-spirobifluorene (12.6 mg, 20 μmol), 4,7-dibromobenzo[c]-1,2,5-thiadiazole (5.9 mg, 20 μmol), 2,7-dibromo-9,9-di(hex-5-en-1-yl)fluorene (64.5 mg, 132 μmol), tris(dibenzylideneacetone)dipalladium(0) (4.6 mg, 5 μmol), tri(o-tolyl)phosphine (9.1 mg, 30 μmol) and hexadecane (171 μL, 585 μmol). The vial was transferred to an argon filled glovebox, sealed with a rubber septum and removed. Toluene (2.19 mL) was added to the vial and the suspension sonicated until a homogenous solution was achieved. The initial aqueous solution was cooled to 0° C. in an ice bath, the ultrasonic probe inserted and the toluene solution injected rapidly into the water. The solution was ultrasonicated for 1 minute, stirred for 30 seconds and ultrasonicated for 1 further minute. The Schlenk tube was sealed, placed in a preheated oil bath at 50° C. and stirred for 20 hours. The Schlenk was opened and a stream of nitrogen gas passed over the emulsion at 50° C., with stirring. The emulsion was cooled to room temperature, the volume increased to 23.0 mL with deionised water and filtered through a glass wool plug. The emulsion was obtained as a milky dark green solution. DLS (water): Z-average=101 nm, Pdl=0.166, D.sub.n=55.1 nm and SD=18.1 nm. UV-Vis Abs. (water): λ.sub.max=381 nm, λ.sub.sec.=453 nm, λ.sub.onset=522 nm. UV-Vis PL (water): λ.sub.max=530 nm.

Example 6—CL-F8T2 CPNs (CL-F8T2/30 are Blue Light Absorbing and Emit Green Light)

(59) This example is not a cross-linked polymer (as required in the present invention), but it will be appreciated by those skilled in the art that one or more crosslinking monomers described herein could be included to form a nanoparticle of the present invention.

(60) Synthesis

(61) ##STR00052##

(62) In a Schlenk tube, sodium dodecyl sulfate (50 mg) was dissolved in deionised water (10 mL) under argon. The solution was degassed by bubbling with argon for 30 minutes. In a separate vial, monomer A (58.6 mg, 9.12×10.sup.−2 mmol), monomer B, monomer C (see amounts in Table 1), monomer D (5.8 mg, 9.12×10.sup.3 mmol), tris(dibenzylideneacetone)dipalladium(0) (0.9 mg, 0.98×10.sup.3 mmol) and tri(o-tolyl)phosphine (1.2 mg, 3.9×10.sup.4 mmol) were dissolved in toluene (1 mL). Hexadecane was added (78 μL) and the mixture was degassed by bubbling with argon for 5 min. After this time, the monomer mixture was then injected to the SDS solution. To promote the miniemulsion, the Schlenk tube was taken to an ice bath and the mixture was sonicated using an ultrasonicator fitted with microtip (Cole Parmer 750 W ultrasonicator, 22% amplitude) for 2 minutes. The tube was resealed and then heated up to 72° C. Once reached this temperature, an aqueous solution of sodium hydroxide 1M (365 μL) was added and the reaction mixture was stirred for 16 h. After cooling down to room temperature, the Schlenk tube was opened and the mixture was stirred for 5 h to remove the residual toluene. To remove SDS, 400 μL of the resulting miniemulsion was diluted with 1.6 mL of deionised water and Amberlite XAD-2 (20 mg) previously washed with water (2×2 mL) was added. The mixture was stirred for 2 hours at room temperature and the Amberlite XAD-2 was removed. Treatment with Amberlite XAD-2 was repeated until the mixture was shaken and no foam formation was longer observed.

(63) Table 5 below shows the amount of monomers B and C used. Table 6 below shows the particle size of the CL-F8T2 CPNs. Table 7 shows the optical properties of CL-F8T2 CPNs in water & THF.

(64) ##STR00053##

(65) TABLE-US-00005 TABLE 5 Initial loading of monomers B and C in CL-F8T2 CPNs Monomer C Monomer B Monomer C Polymer (% mol) (mass, moles) (mass, moles) CL-F8T2/20 20 20 mg 11.8 mg (3.65 × 10.sup.−2 mmol) (3.65 × 10.sup.−3 mmol) CL-F8T2/30 30 10 mg 17.8 mg (1.82 × 10.sup.−2 mmol) (5.48 × 10.sup.−2 mmol)

(66) TABLE-US-00006 TABLE 6 Particle size of CL-F8T2 CPNs in water & THF Water THF D.sub.Num D.sub.Num Polymer d.sub.z (nm) PdI (nm) d.sub.z (nm) PdI (nm) CL-F8T2/20 105 0.158 64 124 0.212 62 CL-F8T2/30 103 0.178 53 120 0.223 63

(67) TABLE-US-00007 TABLE 7 optical properties of CL-F8T2 CPNs in water & THF Water THF Absorption Fluorescence Absorption Fluorescence Polymer λ.sub.max (nm) λ.sub.max (nm) λ.sub.max (nm) λ.sub.max (nm) CL-F8T2/20 386 554 394 525 CL-F8T2/30 431 541 438 498

Example 7—Synthesis of Cross-linked Blue, Green and Red (RGB) Conjugated Polymer Nanoparticles (CPN)s

(68) A series of cross-linked conjugated polymer nanoparticles (CPNs) based on PFO with blue (CL-PFO), green (CL-PFO-BT) and red emission (CL-PFO-DBT.sub.h) were synthesised by miniemulsion polymerisation via Suzuki coupling of 9,9-dioctyl-9H-fluorene-2,7-diboronic acid bis(pinacol) ester (A) with 9,9-dioctyl-2,7-dibromofluorene (B), 2,2′,7,7′-Tetrabromo-9,9′-spirobifluorene (C) and 4,7-dibromo-2,1,3-benzothiadiazole (D) or 4,7-di(4-hexylthien-2-yl)-2,1,3-benzothiadiazole (E) as acceptor units.

(69) ##STR00054##

(70) In a Schlenk tube, sodium dodecyl sulfate (50 mg) was dissolved in deionised water (10 mL) under argon. The solution was degassed by bubbling with argon for 30 minutes. In a separate flask, monomer A (58.6 mg, 9.12×10.sup.−2 mmol), monomer B, monomer C (5.8 mg, 9.12×10.sup.−3 mmol) and monomer D or monomer E (amounts in Table 8) were dissolved in toluene (1 mL), to which hexadecane was added (78 μL) and the mixture was degassed by bubbling with argon for 5 min. After this time, tris(dibenzylideneacetone)dipalladium(0) (0.9 mg, 0.95×10.sup.3 mmol) and tri-(o-tolyl)phosphine (1.2 mg, 3.8×10.sup.−3 mmol) were added to the monomer mixture which was then injected to the SDS solution. To promote the miniemulsion, the Schlenk tube was taken to an ice bath and the mixture was sonicated using an ultrasonicator fitted with microtip (Cole Parmer 750 W ultrasonicator, 22% amplitude) for 2 minutes. The tube was resealed and then heated up to 72° C. Once reached this temperature, an aqueous solution of sodium hydroxide 1M (365 μL) was added and the reaction mixture was stirred for 16 h. After cooling down to room temperature, the Schlenk tube was opened and the mixture was stirred for 5 h to remove the residual toluene. To remove SDS, 400 μL of the resulting miniemulsion was diluted with 1.6 mL of deionised water and Amberlite XAD-2 (20 mg) previously washed with water (2×2 mL) was added. The mixture was stirred for 2 hours at room temperature and the Amberlite XAD-2 was removed. Treatment with Amberlite XAD-2 was repeated until the mixture was shaken and no foam formation was longer observed.

(71) TABLE-US-00008 TABLE 8 Initial loading of monomers B, D and E for synthesis of CL-PFO, CL-PFO-BT and CL-PFO-DBT.sub.h CPNs Acceptor unit Monomer B Monomer D Monomer E Polymer loading (mol %) (mass, moles) (mass, moles) (mass, moles) CL-PFO — 40 mg — — (7.3 ×  10.sup.-2 mmol) CL-PFO-BT 30 mg 5.4 mg 10 (5.47 × (1.82 × — 10.sup.-2 mmol) 10 .sup.-2 mmol) CL-PFO- 35 mg 5.7 mg DBT.sub.h 5 (6.38 × — (9.12 × 10.sup.-2 mmol) 10.sup.-3 mmol)

(72) The introduction of 2,2′,7,7′-Tetrabromo-9,9′-spirobifluorene as cross-linker resulted in CPNs insoluble in different organic solvents (THF, chloroform, toluene, and chlorobenzene). For this reason, determination of molecular weight was not possible. For determination of particle size by DLS, 60 μL of each sample after removal of SDS were diluted with 1 mL of deionised water and the evaluation was carried out using a Malvern Zetasizer Nano ZS.

(73) The particle size of cross-linked blue, green and red-emitting CPNs based on PFO is shown in Table 9:

(74) TABLE-US-00009 TABLE 9 Particle size of CL-PFO, CL-PFO-BT and CL-PFO-DBT.sub.h CPNs determined by DLS. D.sub.Num Polymer M.sub.n (KDa) M.sub.w (KDa) PDI d.sub.z (nm) PdI (nm) CL-PFO — — — 91 0.182 31 CL-PFO-BT — — — 94 0.156 38 CL-PFO-DBT.sub.h — — — 86 0.183 46

(75) The UV-vis absorption spectra of the aqueous dispersion of the cross-linked CPNs were recorded using a Varian Cary 555000UV-Vis-NIR spectrophotometer. Fluorescence spectra of the same samples were recorded on a Varian Cary Eclipse fluorimeter at room temperature at an excitation wavelength of λ=390 nm. The fluorescence quantum yield (QY) was determined using an integration sphere fitted to a Fluorolog 3-22-iHR (Horiba) spectrofluorometer configured with double excitation and emission monochromators with a cooled R928P photomultiplier tube operated in photon-counting mode used as detector. The photophysical properties are displayed in Table 10. The optical properties of cross-linked RGB CPNs were determined in water and in THF.

(76) TABLE-US-00010 TABLE 10 Summary of optical properties of cross-linked RGB CPNs in water. Absorption Fluorescence QY QY Polymer λ.sub.max (nm) λ.sub.max (nm) (%) (StD) CL-PFO 384, 434 438, 465, 501 31 2 CL-PFO-BT 378, 445 533 57 1 CL-PFO-DBT.sub.h 381, 431, 513 620 37 1

(77) The absorption and emission spectra (λ.sub.exc=390 nm) of cross-linked blue, green and red CPNs based on PFO are shown in FIG. 4.

(78) The photophysical properties in THF solution of cross-linked RGB CPNs based on PFO are shown in Table 11.

(79) TABLE-US-00011 TABLE 11 Summary of optical properties of cross-linked RGB CPNs in THF. Absorption Fluorescence QY QY Polymer λ.sub.max (nm) λ.sub.max (nm) (%) (StD) CL-PFO 382, 433 419, 442, 477 75 6 CL-PFO-BT 382, 435 545 99 1 CL-PFO-DBT.sub.h 389, 501 648 76 1

(80) The absorption and emission spectra (λ.sub.exc=390 nm) in THF of cross-linked RGB CPNs based on PFO are shown in FIG. 5.

(81) In order to test the suitability of cross-linked blue, green and red-emitting CPNs in LED illumination as phosphors to produce white light by down-conversion of UV light, a series of acrylic films (thickness=1 mm) containing a ternary mixture of cross-linked RGB CPNs were fabricated and evaluated in a remote phosphor LED array using two different reference UV LED as excitation sources (λ.sub.exc=381 nm and λ.sub.exc=393 nm). To fabricate the films, the CPNs were first precipitated by addition of methanol and centrifugation. Once isolated, the CPNs were redispersed in the commercially available acrylic-based resin Tensol 70. Finally, the curing of the films was carried out under ambient conditions in absence of light. The resulting emission spectra from the films when excited with the UV LED source were recorded with an integrating sphere attached to a Rainbow-Light Micro-Spectrometer MR-16-BINS.

(82) In the first instance, the emission profile of a series of cross-linked RGB CPNs mixtures in water was evaluated to determine the suitable concentration of CPNs in a dispersant medium and the appropriate ratio between each colour CPNs to produce an emission spectrum similar to that exhibited by conventional white LEDs..sup.1-3 To a dispersion of CL-PFO CPNs at 0.05 mol % in water, aliquots of CL-PFO-BT CPNs were gradually added upon reaching a relative intensity ˜0.50 between the emission peak at 530 nm (green emission) and the peak of maximum emission at 467 nm (blue emission). Then, small amounts of an aqueous dispersion of CL-PFO-DBT.sub.h were added to have a final ratio of 100:5:5 (Blue/Green/Red). The progression of the emission profile of the cross-linked RGB CPNs at different ratios is shown in FIG. 6.

(83) Thus, films containing CL-PFO, CL-PFO-BT and CL-DBT.sub.h CPNs at different ratios at a concentration of 0.05 and 0.1 wt. % relative to Tensol 70 were fabricated. The corresponding concentration and ratios between cross-linked blue, green and red CPNs dispersed in the films are presented in Table 12. In FIG. 7, the pictures of Films A-D under visible (top) and UV illumination (bottom) are shown.

(84) TABLE-US-00012 TABLE 12 Concentration of cross-linked blue, green and red CPNs in Films A-D. Blue/ Concentration green/red of CPNs in Film CPNs ratio Tensol (wt. %) A 100:5:1 0.05 B  100:5:2.5 0.05 C 100:5:5 0.05 D   100:5:2.5 0.1
Table 12. Concentration of cross-linked blue, green and red CPNs in Films A-D.

(85) The emission spectra of Films A-D generated when the films are irradiated with two different UV LED sources (λ.sub.exc=381 nm and λ.sub.exc=393 nm) in a remote phosphor LED array are shown in FIG. 8-11.

(86) The Correlated Colour Temperature (CCT), Colour Rendering Index (CRI) and CIE coordinates of the resulting light from Films A-D when irradiated with the reference UV LED source (λ.sub.exc=381 nm) are presented in Table 13. The position of the CIE coordinates in the CIE 1931 chromaticity diagram are displayed in FIG. 12.

(87) TABLE-US-00013 TABLE 13 Correlated Colour Temperature (CCT), Colour Rendering Index (CRI) and CIE coordinates of light emitted by Films A-D when irradiated in a remote phosphor LED array at λ.sub.exc = 381 nm. CIE coordinates Film CCT CRI x Y A 8076 88 0.2908 0.3150 B 7529 87 0.2963 0.3237 C 6108 91 0.3199 0.3317 D 5075 77 0.3475 0.4089

(88) The CCT, CRI and CIE coordinates of the resulting light from Films A-D when irradiated with the reference UV LED source (λ.sub.exc=393 nm) are presented in Table 14. The position of the CIE coordinates in the CIE 1931 chromaticity diagram are displayed in FIG. 13.

(89) TABLE-US-00014 TABLE 14 Correlated Colour Temperature (CCT), Colour Rendering Index (CRI) and CIE coordinates of light emitted by Films A-D when irradiated in a remote phosphor LED array at λ.sub.exc = 393 nm. CIE coordinates Film CCT CRI x y A 32768 29 0.2493 0.2421 B 19179 91 0.2590 0.2571 C 14950 89 0.2740 0.2549 D 6807 81 0.3019 0.3588

Example 8—Synthesis of Cross-Linked White Emitting CPNs Based on PFO

(90) A different approach to generate white light can be achieved by synthesis of one-single cross-linked polymer CPNs based on PFO which emit white light when excited with UV light.

(91) ##STR00055##

(92) In a Schlenk tube was added water (22.0 mL), sodium dodecyl sulfate (110 mg, 382 μmol) and 1M aqueous sodium hydroxide (800 μL, 800 μmol). The solution was purged with argon for 2 hours. In a vial was added 4,7-dibromobenzo[c]-1,2,5-thiadiazole (47 μL of 1 mg mL.sup.−1 in dichloromethane, 160 nmole) and 4,7-bis(5-bromo-4-hexyl-2-thienyl)-2,1,3-benzothiadiazole (50 μL of 1 mg mL.sup.−1 in dichloromethane, 80 nmole) and the solvent was removed using a stream of nitrogen. 9,9-Dioctylfluorene-2,7-diboronic acid bis(1,3-propanediol) ester (111.7 mg, 200 μmol), 9,9-bis(2-ethylhexyl)-2,7-dibromofluorene (87.6 mg, 159.76 μmol), 2,2′,7,7′-tetrabromo-9,9′-spirobifluorene (12.6 mg, 20.0 μmol), tris(dibenzylideneacetone) dipalladium(0) (4.6 mg, 5.0 μmol), tri(o-tolyl)phosphine (9.1 mg, 30 μmol) and hexadecane (171 μL, 585 μmol) were further added to the vial. The vial was transferred to an argon filled glovebox, sealed with a rubber septum and removed. Deoxygenated toluene (2.2 mL) was added to the vial and the suspension sonicated until a homogenous solution was achieved. The initial aqueous solution was cooled to 0° C. in an ice bath, the ultrasonic probe inserted and the toluene solution injected rapidly into the water. The solution was ultrasonicated for 1 minute, stirred for 30 seconds and ultrasonicated for 1 further minute. The Schlenk tube was sealed, placed in a preheated oil bath at 50° C. and stirred for 16 hours. The Schlenk tube was opened and a stream of nitrogen gas passed over the emulsion at, 50° C., with stirring. The emulsion was cooled to room temperature, the volume increased to 23.0 mL using deionised water and filtered through a glass wool plug. The emulsion was obtained as a milky light pink solution.

(93) The particle size of cross-linked white-emitting CPNs based on PFO is shown in Table 15:

(94) TABLE-US-00015 TABLE 15 Particle size of cross-linked white-emitting CPNs determined by DLS. D.sub.Num Polymer M.sub.n (KDa) M.sub.w (KDa) PDI d.sub.z (nm) PdI (nm) CL-PFO-BT-DBT — — — 92 0.187 45

(95) The optical properties of cross-linked white CPNs based on PFO are summarised in Table 16 and their normalised absorption and emission spectra are shown in FIG. 14.

(96) TABLE-US-00016 TABLE 16 Summary of optical properties of cross- linked white-emitting CPNs in water. Emission wavelength Absorption Fluorescence range Polymer λ.sub.max (nm) λ.sub.max (nm) (nm) CL-PFO-BT-DBT 379 427, 448, 400-700 520, 586

(97) Once the CPNs with white emission were successfully synthesised, films containing these particles at 0.05 and 0.1 mol % were fabricated and evaluated in a remote phosphor LED array analogously to the procedure followed for Films A-D. For white-like CPNs the silicon-based resin QLE 1102 was used as dispersant matrix. In FIG. 15, the pictures of Film E and Film F under visible (left) and UV illumination (right) are presented.

(98) The emission spectra of Films E-F generated when the films are irradiated with two different UV LED sources (λ.sub.exc=381 nm and λ.sub.exc=393 nm) in a remote phosphor LED array are shown in FIG. 16-17.

(99) The CCT, CRI and CIE coordinates of the resulting light from Films E-F when irradiated with the reference UV LED source (λ.sub.exc=381 nm) are presented in Table 17. The position of the CIE coordinates in the CIE 1931 chromaticity diagram are displayed in FIG. 18.

(100) TABLE-US-00017 TABLE 17 Correlated Colour Temperature (CCT), Colour Rendering Index (CRI) and CIE coordinates of light emitted by Films E-F when irradiated in a remote phosphor LED array at λ.sub.exc = 381 nm. CIE coordinates Film CCT CRI x y E 6622 81 0.3094 0.3362 F 5654 79 0.3284 0.3762

(101) The CCT, CRI and CIE coordinates of the resulting light from Films E-F when irradiated with the reference UV LED source (λ.sub.exc=393 nm) are presented in Table 18. The position of the CIE coordinates in the CIE 1931 chromaticity diagram are displayed in FIG. 18.

(102) TABLE-US-00018 TABLE 18 Correlated Colour Temperature (CCT), Colour Rendering Index (CRI) and CIE coordinates of light emitted by Films E-F when irradiated in a remote phosphor LED array at λ.sub.exc = 393 nm. CIE coordinates Film CCT CRI x y E — 85 0.2235 0.1745 F 15488 85 0.2606 0.2686

Example 9—5% 9,9′-Spirobifluorene, 80% 9,9-Dioctyl(fluorene) and 10% 9,9-Di(Sodium Undecanoyl Sulfate)(Fluorene) Nanoparticles (which Emit Blue Light)

(103) ##STR00056##

(104) In a two-litre flask was added water (1000 mL) and sodium hydroxide (1.60 g, 32.0 mmol) and the solution purged with argon for 4 hours. In a Schlenk tube was weighed 9,9-di-n-octylfluorene-2,7-diboronic acid bis(propanediol) ester (5.58 g, 10.0 mmol), 9,9-di-n-octyl-2,7-dibromofluorene (3.29 g, 6.00 mmol), 2,2′,7,7′-tetrabromo-9,9′-spirobifluorene (632 mg, 1.00 mmol), tris(dibenzylideneacetone) dipalladium(0) (229 mg, 250 μmol) and tri(o-tolyl)phosphine (456 mg, 1.50 mmol). The Schlenk tube was subjected to 3 argon-vacuum cycles. In a separate Schlenk tube was added toluene (100 mL) and hexadecane (7.73 mL) and the solution purged with argon for 2 hours. This solution was transferred to the former Schlenk tube and the suspension sonicated in an ultrasonic bath until a homogenous solution was achieved. 9,9-Di(sodium undecanoyl sulfate)2,7-dibromofluorene (1.74 g, 2.00 mmol) was added to the initial aqueous solution and cooled to 0° C. in an ice bath. The toluene solution was added rapidly into the aqueous phase under a stream of argon and the ultrasonic probe inserted (½″ replaceable tip) to a depth of 2 cm. The solution was ultrasonicated for 5 minutes at 80% intensity with stirring, stirred for 1 minute and ultrasonicated for 5 further minutes. The flask was sealed, placed in a preheated oil bath at 40° C. and stirred for 20 hours. The flask was opened and air passed over the emulsion at 40° C. for 30 hours, with stirring. The emulsion was cooled to room temperature, left to stand 16 hours and filtered through cotton mesh to provide a suspension (310 g, theoretical 25.9 mg g.sup.−1).

Example 10—5% Benzo[c]-1,2,5-thiadiazole, 5% 9,9′-Spirobifluorene, 75% 9,9-Dioctyl(Fluorene) and 10% 9,9-Di(Sodium Undecanoyl Sulfate)(Fluorene) Nanoparticles (which Emit Green Light)

(105) ##STR00057##

(106) In a one litre flask was added water (800 mL) and 1M aqueous sodium hydroxide (32.0 mL, 32.0 mmol) and the solution purged with argon for 4 hours. In a Schlenk tube was weighed 9,9-di-n-octylfluorene-2,7-diboronic acid bis(propanediol) ester (4.47 g, 8.00 mmol), 9,9-di-n-octyl-2,7-dibromofluorene (2.19 g, 4.00 mmol), 2,2′,7,7′-tetrabromo-9,9′-spirobifluorene (506 mg, 800 μmol), 4,7-dibromobenzo[c]-1,2,5-thiadiazole (235 mg, 800 μmol), tris(dibenzylideneacetone) dipalladium(0) (183 mg, 200 μmol) and tri(o-tolyl)phosphine (365 mg, 1.20 mmol). The Schlenk tube was purged argon for 30 mins. In a separate Schlenk tube was added toluene (80.0 mL) and hexadecane (6.20 mL) and the solution purged with argon for 2 hours. This solution was transferred to the former Schlenk tube and the suspension sonicated in an ultrasonic bath until a homogenous solution was achieved. 9,9-Di(sodium undecanoyl sulfate)2,7-dibromofluorene (1.39 g, 1.60 mmol) was added to the initial aqueous solution and cooled to 0° C. in an ice bath. The toluene solution was added rapidly into the aqueous phase under a stream of argon and the ultrasonic probe inserted (½″ replaceable tip) to a depth of 2 cm. The solution was ultrasonicated for 5 minutes at 60% intensity with stirring, stirred for 1 minute and ultrasonicated at 80% intensity for 5 minutes. The flask was sealed, placed in a preheated oil bath at 40° C. and stirred for 20 hours. The flask was opened and air passed over the emulsion at 100° C. for 15 hours, with stirring. The emulsion was cooled to room temperature and filtered through cotton mesh to provide a suspension (320 g, theoretical 19.2 mg g.sup.−1).

Example 11—5% 4,7-bis(5-hexyl-2-thienyl)-2,1,3-benzothiadiazole, 5% 9,9′-spirobifluorene, 75% 9,9-Dioctyl(fluorene) and 10% 9,9-di(sodium undecanoyl sulfate)(fluorene) Nanoparticles (which Emit Red Light)

(107) ##STR00058##

(108) In a two-litre flask was added water (1000 mL) and sodium hydroxide (1.60 g 32.0 mmol) and the solution purged with argon for 4 hours. In a Schlenk tube was weighed 9,9-di-n-octylfluorene-2,7-diboronic acid bis(propanediol) ester (5.58 g, 10.0 mmol), 9,9-di-n-octyl-2,7-dibromofluorene (2.74 g, 5.00 mmol), 2,2′,7,7′-tetrabromo-9,9′-spirobifluorene (632 mg, 1.00 mmol), 4,7-bis(5-bromo-4-hexyl-2-thienyl)-2,1,3-benzothiadiazole (627 mg, 1.00 mmol), tris(dibenzylideneacetone) dipalladium(0) (229 mg, 250 μmol) and tri(o-tolyl)phosphine (456 mg, 1.50 mmol). The Schlenk tube was subjected to three vacuum-argon cycles. In a separate Schlenk tube was added toluene (100.0 mL) and hexadecane (7.73 mL) and the solution purged with argon for 2 hours. This solution was transferred to the former Schlenk tube and the suspension sonicated in an ultrasonic bath until a homogenous solution was achieved. 9,9-Di(sodium undecanoyl sulfate)2,7-dibromofluorene (1.74 g, 2.00 mmol) was added to the initial aqueous solution and cooled to 0° C. in an ice bath. The toluene solution was added rapidly into the aqueous phase under a stream of argon and the ultrasonic probe inserted (½″ replaceable tip) to a depth of 2 cm. The solution was ultrasonicated for 5 minutes at 80% intensity with stirring, stirred for 1 minute and ultrasonicated for a further 5 minutes. The flask was sealed, placed in a preheated oil bath at 40° C. and stirred for 20 hours. The flask was opened and air passed over the emulsion at 40° C. for 30 hours, with stirring. The emulsion was cooled to room temperature, left to stand for 16 hours and filtered through cotton mesh to provide a suspension (220 g, theoretical 36.1 mg g.sup.−1).

(109) The optical properties of cross-linked blue, green and red are summarised in the table below and their normalised absorption and emission spectra are shown in the FIG. 19.

(110) TABLE-US-00019 TABLE 19 Optical properties of Examples 9-11 in water. Emission Absorption Fluorescence wavelength Polymer λ.sub.max (nm) λ.sub.max (nm) range (nm) Example 9 398 424, 448, 463 400-700 Example 10 394 533 470-700 Example 11 396 620 550-800

Example 12—5% 9,9′-Spirobifluorene, 90% Di((4-((2-ethylhexyl)oxy)phenyl)) fluorene Nanoparticles

(111) ##STR00059##

(112) In a 250 mL round bottom flask, fitted with an argon inlet, was added water (100 mL), sodium hydroxide (160 mg, 4.00 mmol) and sodium dodecyl sulfate (551 mg) and the solution purged with argon for 1 hour. Toluene was degassed with argon for 2 hours. In a Schlenk tube was weighed 9,9-di((4-((2-ethylhexyl)oxy)phenyl))fluorene-2,7-diboronic acid bis(pinacol) ester (827 mg, 1.00 mmol), 2,7-dibromo-9,9-di((4-((2-ethylhexyl)oxy)phenyl))fluorene (513 mg, 700 μmol), 2,2′,7,7′-tetrabromo-9,9′-spirobifluorene (63.2 mg, 100 μmol), hexadecane (855 μL), 4,7-dibromobenzo[c]-1,2,5-thiadiazole (29.4 mg, 100 μmol), tris(dibenzylideneacetone) dipalladium(0) (22.4 mg, 25 μmol) and tri(o-tolyl)phosphine (45.6 mg, 150 μmol). The Schlenk tube was subjected to four vacuum-argon cycles. Toluene (10 mL) was added and the suspension sonicated in an ultrasonic bath until a homogenous solution was achieved. The initial aqueous solution was cooled to 0° C. in an ice bath and the toluene solution was added rapidly into the aqueous phase under a stream of argon. A stirrer bar was added and the ultrasonic probe inserted (½″ extender tip) to a depth of 2 cm. The solution was ultrasonicated for 2 minutes at 40% amplitude, stirred for 30 seconds then sonicated for 2 further minutes. The flask was sealed, placed in a preheated oil bath at 70° C. and stirred for 16 hours. The flask was cooled to 50° C. and air passed over the emulsion for 5 hours, with stirring. The emulsion was cooled to room temperature, left to stand for 16 hours and filtered through a glass wool plug. The emulsion was obtained as a bright green cloudy dispersion. DLS: z-Average: 115.9 nm, Pdl: 0.153. UV-Vis Abs. (water): λ.sub.max=391 nm. UV-Vis PL (water): λ.sub.max=422 nm.

Example 13—5% 9,9′-Spirobifluorene, 10% Di((4-(sodium undecanoyl sulfate)phenyl))fluorene, 80% Di((4-((2-ethylhexyl)oxy)phenyl))fluorene Nanoparticles

(113) ##STR00060##

(114) In a 250 mL round bottom flask, fitted with an argon inlet, was added water (100 mL), sodium hydroxide (160 mg, 4.00 mmol) and 2,7-dibromo-9,9-di((4-(sodium undecanoyl sulfate)phenyl))fluorene (211 mg, 200 μmol) and the solution purged with argon for 2 hours. Toluene was degassed with argon for 2 hours. In a Schlenk tube was weighed 9,9-di((4-((2-ethylhexyl)oxy)phenyl))fluorene-2,7-diboronic acid bis(pinacol) ester (827 mg, 1.00 mmol), 2,7-dibromo-9,9-di((4-((2-ethylhexyl)oxy)phenyl))fluorene (440 mg, 600 μmol), 2,2′,7,7′-tetrabromo-9,9′-spirobifluorene (63.2 mg, 100 μmol), hexadecane (855 μL), tris(dibenzylideneacetone) dipalladium(0) (22.4 mg, 25 μmol) and tri(o-tolyl)phosphine (45.6 mg, 150 μmol). The Schlenk tube was subjected to four vacuum-argon cycles. Toluene (10 mL) was added and the suspension sonicated in an ultrasonic bath until a homogenous solution was achieved. A stirrer bar was added and the ultrasonic probe inserted (½″ extender tip) to a depth of 2 cm. The solution was ultrasonicated for 2 minutes at 40% amplitude, stirred for 30 seconds then sonicated for 2 further minutes. The flask was sealed, placed in a preheated oil bath at 60° C. and stirred for 16 hours. The flask was cooled to 50° C. and air passed over the emulsion for 5 hours, with stirring. The emulsion was cooled to room temperature, left to stand for 16 hours and filtered through a glass wool plug. The emulsion was obtained as a dark green/grey cloudy dispersion. DLS: z-Average: 171.2 nm, Pdl: 0.047. UV-Vis Abs. (water): λ.sub.max=398 nm. UV-Vis PL (water): λ.sub.max=422 nm.

Example 14—5% Benzo[c]-1,2,5-thiadiazole, 5% 9,9′-Spirobifluorene, 85% Di((4-((2-ethylhexyl)oxy)phenyl))fluorene Nanoparticles

(115) ##STR00061##

(116) In a 250 mL round bottom flask, fitted with an argon inlet, was added water (100 mL), sodium hydroxide (160 mg, 4.00 mmol) and sodium dodecyl sulfate (551 mg) and the solution purged with argon for 1 hour. Toluene was degassed with argon for 2 hours. In a Schlenk tube was weighed 9,9-di((4-((2-ethylhexyl)oxy)phenyl))fluorene-2,7-diboronic acid bis(pinacol) ester (827 mg, 1.00 mmol), 2,7-dibromo-9,9-di((4-((2-ethylhexyl)oxy)phenyl))fluorene (513 mg, 700 μmol), 2,2′,7,7′-tetrabromo-9,9′-spirobifluorene (63.2 mg, 100 μmol), hexadecane (855 μL), 4,7-dibromobenzo[c]-1,2,5-thiadiazole (29.4 mg, 100 μmol), tris(dibenzylideneacetone) dipalladium(0) (22.4 mg, 25 μmol) and tri(o-tolyl)phosphine (45.6 mg, 150 μmol). The Schlenk tube was subjected to four vacuum-argon cycles. Toluene (10 mL) was added and the suspension sonicated in an ultrasonic bath until a homogenous solution was achieved. The initial aqueous solution was cooled to 0° C. in an ice bath and the toluene solution was added rapidly into the aqueous phase under a stream of argon. A stirrer bar was added and the ultrasonic probe inserted (½″ extender tip) to a depth of 2 cm. The solution was ultrasonicated for 2 minutes at 40% amplitude, stirred for 30 seconds then sonicated for 2 further minutes. The flask was sealed, placed in a preheated oil bath at 70° C. and stirred for 16 hours. The flask was cooled to 50° C. and air passed over the emulsion for 5 hours, with stirring. The emulsion was cooled to room temperature, left to stand for 16 hours and filtered through a glass wool plug. The emulsion was obtained as a bright green cloudy dispersion. DLS: z-Average: 115.1 nm, Pdl: 0.160. UV-Vis Abs. (water): λ.sub.max=387 nm. UV-Vis PL (water): λ.sub.max=526 nm.

Example 15—5% Benzo[c]-1,2,5-thiadiazole, 5% 9,9′-Spirobifluorene, 10% Di((4-(sodium undecanoyl sulfate)phenyl))fluorene, 75% Di((4-((2-ethylhexyl)oxy)phenyl))fluorene Nanoparticles

(117) ##STR00062##

(118) In a 250 mL round bottom flask, fitted with an argon inlet, was added water (100 mL), sodium hydroxide (160 mg, 4.00 mmol) and 2,7-dibromo-9,9-di((4-(sodium undecanoyl sulfate)phenyl))fluorene (211 mg, 200 μmol) and the solution purged with argon for 1 hour. Toluene was degassed with argon for 1 hours. In a Schlenk tube was weighed 9,9-di((4-((2-ethylhexyl)oxy)phenyl))fluorene-2,7-diboronic acid bis(pinacol) ester (827 mg, 1.00 mmol), 2,7-dibromo-9,9-di((4-((2-ethylhexyl)oxy)phenyl))fluorene (366 mg, 500 μmol), 2,2′,7,7′-tetrabromo-9,9′-spirobifluorene (63.2 mg, 100 μmol), hexadecane (855 μL), 4,7-dibromobenzo[c]-1,2,5-thiadiazole (29.4 mg, 100 μmol), tris(dibenzylideneacetone) dipalladium(0) (22.4 mg, 25 μmol) and tri(o-tolyl)phosphine (45.6 mg, 150 μmol). The Schlenk tube was subjected to four vacuum-argon cycles. Toluene (10 mL) was added and the suspension sonicated in an ultrasonic bath until a homogenous solution was achieved. The initial aqueous solution was cooled to 0° C. in an ice bath and the toluene solution was added rapidly into the aqueous phase under a stream of argon. A stirrer bar was added and the ultrasonic probe inserted (½″ extender tip) to a depth of 2 cm. The solution was ultrasonicated for 2 minutes at 40% amplitude, stirred for 30 seconds then sonicated for 2 further minutes. The flask was sealed, placed in a preheated oil bath at 70° C. and stirred for 16 hours. The flask was cooled to 50° C. and air passed over the emulsion for 5 hours, with stirring. The emulsion was cooled to room temperature, left to stand for 16 hours and filtered through a glass wool plug. The emulsion was obtained as a bright green cloudy dispersion. DLS: z-Average: 184.5 nm, Pdl: 0.031. UV-Vis Abs. (water): λ.sub.max=393 nm. UV-Vis PL (water): λ.sub.max=527 nm.

Example 16—5% Benzo[c]-1,2,5-thiadiazole, 5% 9,9′-Spirobifluorene, 75% 9,9-Dioctyl(fluorene), 10% 9,9-Di(poly(ethylene glycol) monomethyl ether.SUB.(Mn 900).)(fluorene)

(119) ##STR00063##

(120) In a Schlenk tube was added water (20 mL) and sodium hydroxide (32.0 mg, 800 μmol) and the solution purged with argon for 2 hours. Toluene was degassed with argon for 2 hours. In a vial was weighed 9,9-di-n-octylfluorene-2,7-diboronic acid bis(propanediol) ester (111.7 mg, 200 μmol), 9,9-di-n-octyl-2,7-dibromofluorene (54.8 mg, 100 μmol), 2,2′,7,7′-tetrabromo-9,9′-spirobifluorene (12.6 mg, 20 μmol), 2,7-dibromo-9,9-di((poly(ethylene glycol) monomethyl ether.sub.(Mn 900))phenyl))fluorene (86.3 mg, 40 μmol), 4,7-dibromobenzo[c]-1,2,5-thiadiazole (5.9 mg, 20 μmol), hexadecane (150 μL), tris(dibenzylideneacetone) dipalladium(0) (4.6 mg, 5 μmol) and tri(o-tolyl)phosphine (9.1 mg, 30 μmol). The vial was purged with argon for 30 minutes. Toluene (2.00 mL) was added and the suspension sonicated in an ultrasonic bath until a homogenous solution was achieved. The initial aqueous solution and cooled to 0° C. in an ice bath. The toluene solution was added rapidly into the aqueous phase under a stream of argon. A stirrer bar was added and the ultrasonic probe inserted (6 mm microtip) to a depth of 2 cm. The solution was ultrasonicated for 1 minute at 30% amplitude, stirred for 30 seconds and sonicated for 1 further minute. The flask was sealed, placed in a preheated oil bath at 40° C. and stirred for 20 hours. The flask was heated to 50° C. and air passed over the emulsion for 5 hours, with stirring. The emulsion was cooled to room temperature, left to stand for 16 hours and filtered through cotton mesh. The emulsion was obtained as a bright green cloudy dispersion.

Example 17—5% Benzo[c]-1,2,5-thiadiazole, 5% 9,9′-Spirobifluorene, 74% 9,9-Dioctyl(fluorene), 10% 9,9-Di(sodium undecanoyl sulfate)(fluorene), 1% 9,9-Di(sodium undecanoyl carboxylate)(fluorene)

(121) ##STR00064##

(122) In a Schlenk tube was added water (20 mL) and sodium hydroxide (32.0 mg, 800 μmol) and the solution purged with argon for 2 hours. Toluene was degassed with argon for 2 hours. In a vial was weighed 9,9-di-n-octylfluorene-2,7-diboronic acid bis(propanediol)ester (111.7 mg, 200 μmol), 9,9-di-n-octyl-2,7-dibromofluorene (41.7 mg, 76 μmol), 2,2′,7,7′-tetrabromo-9,9′-spirobifluorene (12.6 mg, 20 μmol), 2,7-dibromo-9,9-di(undecanoic acid)fluorene (2.8 mg, 4.0 μmol), 4,7-dibromobenzo[c]-1,2,5-thiadiazole (5.9 mg, 20 μmol), tris(dibenzylideneacetone) dipalladium(0) (4.6 mg, 50 mol) and tri(o-tolyl)phosphine (9.1 mg, 30 μmol). The vial was purged with argon for 30 minutes. Toluene (2.00 mL) was added and the suspension sonicated in an ultrasonic bath until a homogenous solution was achieved. 9,9-Di(sodium undecanoyl sulfate)2,7-dibromofluorene (34.7 mg, 40 μmol) was added to the initial aqueous solution and cooled to 0° C. in an ice bath. The toluene solution was added rapidly into the aqueous phase under a stream of argon. A stirrer bar was added and the ultrasonic probe inserted (6 mm microtip) to a depth of 2 cm. The solution was ultrasonicated for 2 minutes at 30% amplitude, stirred for 30 seconds and this sequence repeated four further times. The flask was sealed, placed in a preheated oil bath at 4000 and stirred for 20 hours. The flask was heated to 50° C. and air passed over the emulsion for 7 hours, with stirring. The emulsion was cooled to room temperature and filtered through a glass wool plug. The emulsion was obtained as a bright green cloudy dispersion.

Example 18—5% Benzo[c]-1,2,5-thiadiazole, 5% 9,9′-Spirobifluorene, 70% 9,9-Dioctyl(fluorene), 10% 9,9-Di(sodium undecanoyl sulfate)(fluorene), 5% 9,9-Di(sodium undecanoyl carboxylate)(fluorene)

(123) ##STR00065##

(124) In a Schlenk tube was added water (20 mL) and sodium hydroxide (33.6 mg, 840 μmol) and the solution purged with argon for 2 hours. Toluene was degassed with argon for 2 hours. In a vial was weighed 9,9-di-n-octylfluorene-2,7-diboronic acid bis(propanediol) ester (111.7 mg, 200 μmol), 9,9-di-n-octyl-2,7-dibromofluorene (43.9 mg, 80 μmol), 2,7-dibromo-9,9-di(undecanoic acid)fluorene (13.9 mg, 20.0 μmol), 2,2′,7,7′-tetrabromo-9,9′-spirobifluorene (12.6 mg, 20 μmol), 4,7-dibromobenzo[c]-1,2,5-thiadiazole (5.9 mg, 20 μmol), hexadecane (150 μL), tris(dibenzylideneacetone) dipalladium(0) (4.6 mg, 5 μmol) and tri(o-tolyl)phosphine (9.1 mg, 30 μmol). The vial was purged with argon for 30 minutes. Toluene (2.00 mL) was added and the suspension sonicated in an ultrasonic bath until a homogenous solution was achieved. 9,9-Di(sodium undecanoyl sulfate)2,7-dibromofluorene (34.7 mg, 40 μmol) was added to the initial aqueous solution and cooled to 0° C. in an ice bath. The toluene solution was added rapidly into the aqueous phase under a stream of argon. A stirrer bar was added and the ultrasonic probe inserted (6 mm microtip) to a depth of 2 cm. The solution was ultrasonicated for 2 minutes at 30% amplitude, stirred for 30 seconds and this sequence repeated four further times. The flask was sealed, placed in a preheated oil bath at 40° C. and stirred for 20 hours. The flask was heated to 50° C. and air passed over the emulsion for 5 hours, with stirring. The emulsion was cooled to room temperature and filtered through a glass wool plug. The emulsion was obtained as a bright green slightly cloudy dispersion. DLS: z-Average: 77.1 nm, Pdl: 0.211.

Example 19—5% Benzo[c]-1,2,5-thiadiazole, 5% 9,9′-Spirobifluorene, 70% 9,9-Dioctyl(fluorene), 10% 9,9-Di(sodium undecanoyl sulfate)(fluorene), 5% 9,9-Di(sodium undecanoyl carboxylate)(fluorene)

(125) ##STR00066##

(126) In a Schlenk tube was added water (20 mL) and sodium hydroxide (33.6 mg, 840 μmol) and the solution purged with argon for 2 hours. Toluene was degassed with argon for 2 hours. In a vial was weighed 9,9-di-n-octylfluorene-2,7-diboronic acid bis(propanediol) ester (111.7 mg, 200 μmol), 9,9-di-n-octyl-2,7-dibromofluorene (43.9 mg, 80 μmol), 2,7-dibromo-9,9-di(undecanoic acid)fluorene (13.9 mg, 20.0 μmol), 2,2′,7,7′-tetrabromo-9,9′-spirobifluorene (12.6 mg, 20 μmol), 4,7-dibromobenzo[c]-1,2,5-thiadiazole (5.9 mg, 20 μmol), tris(dibenzylideneacetone) dipalladium(0) (4.6 mg, 5 μmol) and tri(o-tolyl)phosphine (9.1 mg, 30 μmol). The vial was purged with argon for 30 minutes. Toluene (2.00 mL) was added and the suspension sonicated in an ultrasonic bath until a homogenous solution was achieved. 9,9-Di(sodium undecanoyl sulfate)2,7-dibromofluorene (34.7 mg, 40 μmol) was added to the initial aqueous solution and cooled to 0° C. in an ice bath. The toluene solution was added rapidly into the aqueous phase under a stream of argon. A stirrer bar was added and the ultrasonic probe inserted (6 mm microtip) to a depth of 2 cm. The solution was ultrasonicated for 2 minutes at 30% amplitude, stirred for 30 seconds and this sequence repeated four further times. The flask was sealed, placed in a preheated oil bath at 40° C. and stirred for 20 hours. The flask was heated to 50° C. and air passed over the emulsion for 5 hours, with stirring. The emulsion was cooled to room temperature and filtered through a glass wool plug. The emulsion was obtained as a bright green clear dispersion. DLS: z-Average: 67.6 nm, Pdl: 0.237. UV-Vis Abs. (water): λ.sub.max=375 nm. UV-Vis PL (water): λ.sub.max=536 nm.

Example 20—LED Devices

(127) In order to test the suitability of cross-linked blue, green, and red, nanoparticles in LED illumination as phosphors for down-conversion of UV light, a series of silicone-based films (thickness=0.5 mm) containing blue, green or red nanoparticles was fabricated (Films G-I) and evaluated in a remote phosphor LED array using a reference UV LED as excitation source (λ.sub.exc=385 nm). To fabricate the films, the nanoparticles were first precipitated by addition of isopropanol and centrifugation. Once isolated, the nanoparticles were redispersed in the Part A of the commercially available silicone-based resin QLE 1102. Having obtained a uniform dispersion, the Part B of the resin QLE 1102 was added in a ratio 1:1 relative to the Part A. The concentration of the nanoparticles within the film was 0.67 wt % relative to QLE 1102 (Part A+Part B). Finally, the curing of the films was carried out under ambient conditions in absence of light. The resulting emission spectra from the films when excited with the UV LED source were recorded with an integrating sphere attached to a Rainbow-Light Micro-Spectrometer MR-16-BINS.

(128) Following a similar approach used to produce white light from a combination of cross-linked blue, green and red nanoparticles which down-converts the energy from a UV source, a series of silicone-based films (thickness=0.5 mm) containing a ternary mixture of cross-linked nanoparticles was fabricated (Film J and Film K) and evaluated in a remote phosphor LED array using a reference UV LED as excitation source (λ.sub.exc=385 nm). The films were fabricated using a similar methodology to that followed to fabricate Films G-I. The overall concentration of CPNs within the films was 0.67 wt. % and the corresponding ratios between cross-linked blue, green and red nanoparticles dispersed in the films are presented in Table 20. In FIG. 22, the emission spectra of Films J (left) and K (right) generated when the films are irradiated with a UV LED source (λ.sub.exc=385 nm) in a remote phosphor LED array are shown.

(129) TABLE-US-00020 TABLE 20 Ratio between cross-linked blue, green and red nano- particles in Films J and K. Blue/green/red Film CPNs ratio J 100:3:1.5 K 100:5:2.5

(130) The Correlated Colour Temperature (CCT), Colour Rendering Index (CRI) and CIE coordinates of the resulting light from Films J and K when irradiated with the reference UV LED source (λ.sub.exc=385 nm) are presented in Table 21. The position of the CIE coordinates in the CIE 1931 chromaticity diagram are displayed in FIG. 23.

(131) TABLE-US-00021 TABLE 21 Correlated Colour Temperature (CCT), Colour Rendering Index (CRI) and CIE coordinates of light emitted by Films J and K when irradiated in a remote phosphor LED array at λ.sub.exc = 385 nm. CIE coordinates CCT CRI x y J 6867.02 85.88 0.3058 0.3306 K 5339.02 82.40 0.3368 0.3637

(132) The use of cross-linked nanoparticles as phosphors for down-conversion of blue light was also studied. The combination of blue light from the LED source and the emission from the nanoparticles resulted in white emission. To corroborate this, a series of silicone-based films (thickness=0.5 mm) containing 0.5 wt. % nanoparticles (Film L) or a mixture of green and red nanoparticles at different ratios was prepared (Film M and Film N) and then evaluated in a remote phosphor LED array using a primary blue LED as excitation source (λ.sub.exc=450 nm). The corresponding ratios between cross-linked green and red nanoparticles dispersed in Films M and N are presented in Table 22. The resulting emission spectra resulting from Films L-N when excited with the blue LED source are shown in FIG. 24.

(133) TABLE-US-00022 TABLE 22 Ratio between cross-linked green and red nanoparticles in Films M and N. Green/red nanoparticle Film s ratio M 20:1 N 10:1

(134) The Correlated Colour Temperature (CCT), Colour Rendering Index (CRI) and CIE coordinates of the resulting light from Films L-N when irradiated with the reference blue LED source (λ.sub.exc=450 nm) are presented in Table 23. The position of the CIE coordinates in the CIE 1931 chromaticity diagram are displayed in FIG. 25.

(135) TABLE-US-00023 TABLE 23 Correlated Colour Temperature (CCT), Colour Rendering Index (CRI) and CIE coordinates of light emitted by Films L-N when irradiated in a remote phosphor LED array at λ.sub.exc = 450 nm. CIE coordinates CCT CRI x y L 6543.94 57.39 0.3035 0.3869 M 4544.34 66.11 0.368 0.4144 N 4268.73 74.98 0.3714 0.379

Example 21—5% Benzo[c]-1,2,5-thiadiazole, 5% 9,9′-Spirobifluorene 85% Spiroanthracenefluorene

(136) ##STR00067##

(137) In a Schlenk tube was added water (22.0 mL), sodium dodecyl sulfate (110 mg, 382 μmol) and 1M aqueous sodium hydroxide (800 μL, 800 mol). The solution was purged with argon for 2 hours. In a vial was weighed compound 1 (68.3 mg, 14 μmol), compound 2 (116.5 mg, 200 μmol), 4,7-dibromobenzo[c]-1,2,5-thiadiazole (5.9 mg, 20 μmol), tris(dibenzylideneacetone)dipalladium(0) (4.6 mg, 5 μmol), tri(o-tolyl)phosphine (9.1 mg, 3 μmol), 2,2′,7,7′-tetrabromo-9,9′-spirobifluorene (12.6 mg, 20 μmol) and hexadecane (171 μL, 585 μmol). The vial was sealed with a rubber septum and subjected to three vacuum-argon cycles. In a separate Schlenk tube, toluene was degassed by purging with argon for 2 hours. Toluene (2.2 mL) was added to the vial and the suspension sonicated until a homogenous solution was achieved. The initial aqueous solution was cooled to 0° C. in an ice bath, the ultrasonic probe inserted and the toluene solution injected rapidly into the water. The solution was ultrasonicated for 1 minute, mixed for approx. 30 seconds and ultrasonicated for 1 further minute. The Schlenk tube was sealed, placed in a preheated oil bath at 72° C. and stirred for 20 hours. The Schlenk tube was opened and a stream of nitrogen gas passed over the emulsion at 50° C. for 5 hours, with stirring and additional deionised water added throughout to keep volume ˜23.0 mL. The emulsion was cooled to room temperature, the volume increased to 23.0 mL with deionised water and filtered through a glass wool plug. The emulsion was obtained as a bright green dispersion. UV-Vis Abs. (water): λ.sub.max=380 nm. UV-Vis PL (water): λ.sub.max=529 nm.

(138) The suitability of Example 21 as phosphor for down-conversion of LED-light was tested by the evaluation of a series of silicone-based films (thickness=0.5 mm) at 0.3, 0.5 and 0.67 wt. % (Films O-Q) in a remote phosphor LED array using a LED excitation source (λ.sub.exc=385 nm). To fabricate the films, the CPNs were first precipitated by addition of a KCl solution (1 M) and centrifugation. Once isolated, the CPNs were redispersed in the Part A of the commercially available silicone-based resin OLE 1102. Having obtained a uniform dispersion, the Part B of the resin QLE 1102 was added in a ratio 1:1 relative to the Part A. Finally, the curing of the films was carried out under ambient conditions in absence of light. The resulting emission spectra from Films O-Q when excited with the LED light source recorded with an integrating sphere attached to a Rainbow-Light Micro-Spectrometer MR-16-BINS are shown in FIG. 26.

(139) The suitability of Example 21 as phosphors for down-conversion of blue light was confirmed by the evaluation of Films O-Q in a remote phosphor LED array using a blue LED as the excitation source (λ.sub.exc=450 nm). The partial down-conversion of blue light by Film O combined with the emission of Example 21 nanoparticles contained within this film resulted in white emission. The resulting emission spectra from Films O-Q when excited with the blue LED source are shown in FIG. 27.

(140) TABLE-US-00024 TABLE 24 Correlated Colour Temperature (CCT), Colour Rendering Index (CRI) and CIE coordinates of light emitted by Films O-Q when irradiated in a remote phosphor LED array at λ.sub.exc = 450 nm. CIE coordinates CCT CRI x y O 10444.37 65.71 0.2638 0.3118 P 5207.19 52.69 0.3481 0.5039 Q 4730.46 42.86 0.3805 0.56

(141) FIG. 28 shows the position in the CIE 1931 chromaticity diagram of light emitted by Films O-Q when irradiated in a remote phosphor LED array at λ.sub.exc=450 nm.