BLUE FILTERS COMPRISING SEMICONDUCTOR NANOPARTICLES AND USES THEREOF

Abstract

A light filtering material including at least one matrix material; and semi-conductive nanoparticles which are dispersed in the matrix material. The light filtering material has: a local maximum absorbance of highest wavelength in the range from 350 to 500 nm, the local maximum has an absorbance value A.sub.max for a wavelength .sub.max; a value of 0.9A.sub.max for a wavelength .sub.0.9, .sub.0.9 being greater than .sub.max; a value of 0.5A.sub.max for a wavelength .sub.0.5, .sub.0.5 being greater than .sub.0.9; and |.sub.0.5.sub.0.9| is less than 15 nm.

Claims

1-15. (canceled)

16. A light filtering material comprising: a) at least one matrix material; and b) semi-conductive nanoparticles which are dispersed in said matrix material; and wherein said light filtering material absorbs light, and wherein absorbance of said light filtering material has: a local maximum absorbance of highest wavelength in the range from 350 to 500 nm, said local maximum having an absorbance value A.sub.max for a wavelength .sub.max, a value of 0.9A.sub.max for a wavelength .sub.0.9, .sub.0.9 being greater than .sub.max; a value of 0.5A.sub.max for a wavelength .sub.0.5, .sub.0.5 being greater than .sub.0.9; and wherein |.sub.0.5.sub.0.9| is less than 15 nm.

17. The light filtering material according to claim 16, wherein absorbance of said light filtering material has a value of 0.1A.sub.max for a wavelength .sub.0.1, .sub.0.1 being greater than .sub.0.9; and wherein |.sub.0.1.sub.0.9| is less than 30 nm.

18. The light filtering material according to claim 16, wherein the semi-conductive nanoparticles comprise a material of formula
M.sub.xQ.sub.yE.sub.zA.sub.w(I), wherein: M is selected from the group consisting of Zn, Cd, Hg, Cu, Ag, Au, Ni, Pd, Pt, Co, Fe, Ru, Os, Mn, Tc, Re, Cr, Mo, W, V, Nd, Ta, Ti, Zr, Hf, Be, Mg, Ca, Sr, Ba, Al, Ga, In, Tl, Si, Ge, Sn, Pb, As, Sb, Bi, Sc, Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Cs or a mixture thereof; Q is selected from the group consisting of Zn, Cd, Hg, Cu, Ag, Au, Ni, Pd, Pt, Co, Fe, Ru, Os, Mn, Tc, Re, Cr, Mo, W, V, Nd, Ta, Ti, Zr, Hf, Be, Mg, Ca, Sr, Ba, Al, Ga, In, Tl, Si, Ge, Sn, Pb, As, Sb, Bi, Sc, Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Cs or a mixture thereof; E is selected from the group consisting of O, S, Se, Te, C, N, P, As, Sb, F, Cl, Br, I, or a mixture thereof; A is selected from the group consisting of O, S, Se, Te, C, N, P, As, Sb, F, Cl, Br, I, or a mixture thereof; and x, y, z and w are independently a decimal number from 0 to 5; x, y, z and w are not simultaneously equal to 0; x and y are not simultaneously equal to 0; z and w may not be simultaneously equal to 0.

19. The light filtering material according to claim 16, wherein the semi-conductive nanoparticles are nanospheres, nanoplates or nanorods.

20. The light filtering material according to claim 16, wherein the semi-conductive nanoparticles are homostructures.

21. The light filtering material according to claim 16, wherein the semi-conductive nanoparticles are core/shell nanoparticles or core/crown nanoparticles, the core being a different material from the shell or crown.

22. The light filtering material according to claim 16, wherein the amount of semi-conductive nanoparticles in the light filtering is from 10 ppm to 10 wt %, based on the weight of the light filtering material.

23. The light filtering material according to claim 16, wherein the semi-conductive nanoparticles are capped with an organic layer, an inorganic layer or a mixture thereof, and/or encapsulated in an inorganic matrix.

24. The light filtering material according to claim 16, wherein the matrix material is an organic material or an inorganic material.

25. The light filtering material according to claim 24, wherein the organic material is selected from allyl polymers, (meth)acrylic polymers; epoxy compounds; polyurethane, polythiourethane materials, or mixture thereof.

26. The light filtering material according to claim 24, wherein the inorganic material is selected from sol gel materials, mineral oxides, or mixture thereof.

27. A display comprising an image producing system and a light filtering material according to claim 16.

28. A light filtering glass container comprising glass container partially or totally coated with the light filtering material according to claim 16.

29. An ophthalmic lens comprising the light filtering material according to claim 16.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0188] FIG. 1 is a schematic representation of various shapes (spheres and plates) and structure (homostructure, core/shell, core/crown, dot in plate) of semi-conductive nanoparticles.

[0189] FIG. 2 shows the absorbance curves as a function of light wavelength (in nm) of a first population of ZnSe nanospheres NP1 (dotted line), of a second population of ZnSe nanospheres NP2 (semi-dotted line), of a third population of ZnSe nanospheres NP3 (black solid line) and of a fourth population of ZnSe nanospheres NP4 (grey solid line).

[0190] FIG. 3 shows the absorbance curves as a function of light wavelength (in nm) of CdS nanoplates in heptane (semi-dotted line), of CdS-MPA nanoparticles in water (dotted line) and of lens S1 comprising Diethylene glycol bis(allyl carbonate) and CdS nanoplates (solid line).

[0191] FIG. 4.1 shows the absorbance curves as a function of light wavelength (in nm) of ZnSe nanospheres in toluene (semi-dotted line), of encapsulated ZnSe nanospheres in methanol (dotted line) and of lens S2 comprising a Sol-Gel coating comprising ZnSe nanospheres (solid line).

[0192] FIG. 4.2 shows the absorbance curves as a function of light wavelength (in nm) of ZnSe nanoplates in toluene (semi-dotted line), of encapsulated ZnSe nanoplates in methanol (dotted line) and of lens S3 comprising a Sol-Gel coating comprising ZnSe nanoplates (solid line).

[0193] FIG. 5 shows transmission curves T of a comparative bottle B0 and a bottle B1 coated with a light filtering material according to this disclosure, as a function of light wavelength (in nm).

[0194] FIG. 6 illustrates a structure of a display as disclosed herein.

[0195] FIG. 7 is a graph showing a chromaticity space CIE xy, with the gamut defined from three light sources: red (R), green (G) and blue (B) without light filtering material and with light filtering material (blue source is shifted from B to B).

[0196] FIG. 8 shows intensity of white light (Iin arbitrary unit) emitted by a display as a function of light wavelength (in nm) without light filtering material (L0) and with light filtering material L1.

EXAMPLES

[0197] The present invention is further illustrated by the following examples.

Example 1a: Absorbance of Dispersion Comprising ZnSe Nanospheres

[0198] Semi-conductive nanoparticles of formula ZnSe (hereafter NP1) and having a shape of sphere with diameter of 5.40.2 nm were prepared according to procedure known by the man of the art and reported in New J. Chem., 2007, 31, 1843-1852. Specific purification steps included selective precipitation and redispersion in presence of organic ligands as alkylamines. A monodisperse population of ZnSe nanospheres (NP1) was obtained with a coefficient of variation inferior to 20%.

[0199] Similar experiment was conducted to synthesize ZnSe nanospheres, respectively with a diameter of 5.80.2 nm (NP2), 6.40.2 nm (NP3), 6.80.2 nm (NP4) and 7.40.2 nm (NP5). The same purification steps were used to obtain monodisperse populations of ZnSe nanospheres with a coefficient of variation inferior to 20%.

[0200] Absorbance curves of the first population of ZnSe nanospheres NP1 (dotted line), second population of ZnSe nanospheres NP2 (semi-dotted line), third population of ZnSe nanospheres NP3 (black line) and fourth population of ZnSe nanospheres NP4 (grey solid line) were measured as a function of light wavelength in the UV-visible and are shown on FIG. 2. Table 2 summarizes the results obtained for NP1-NP5.

[0201] An increase of .sub.max value was observed when increasing the diameter of ZnSe nanospheres.

TABLE-US-00002 TABLE 2 Table 2: Results obtained for ZnSe populations NP1-NP5. NP1 NP2 NP3 NP4 NP5 diameter (nm) 5.4 0.2 5.8 0.2 6.4 0.2 6.8 0.2 7.4 0.2 .sub.max (nm) 405 412 419 424 430 (0.9*A.sub.max) (nm) 409 415 422 428 434 (0.5*A.sub.max) (nm) 415 420 427 432 438 (0.1*A.sub.max) (nm) 426 430 435 440 447 |.sub.0.5 .sub.0.9| (nm) 6 5 5 4 4 |.sub.0.1 .sub.0.9| (nm) 17 15 13 12 13

Example 1b: Absorbance of CdSe Nanoparticles (Comparative)

[0202] Semi-conductive nanoparticles of formula CdSe and having a shape of plate with length of 10 nm; width of 20 nm and thickness of 1.2 nm (corresponding to 4 monolayers) were prepared according to procedure disclosed in EP2633102.

[0203] Table 3 summarizes the results obtained for CdSe nanoplates dispersion. The dispersion of CdSe nanoplates does not exhibit .sub.max ranging from 350 to 500 nm.

TABLE-US-00003 TABLE 3 Table 3: Results obtained for CdSe nanoplates dispersion. CdSe (4 monolayers .sub.max 512 nm (0.9*A.sub.max) 514 nm (0.5*A.sub.max) 516 nm (0.1*A.sub.max) 520 nm |.sub.0.5 .sub.0.9| 2 nm |.sub.0.1 .sub.0.9| 6 nm

Example 2: Ophthalmic Lens Fabricated from a Polymerizable Composition Comprising Diethylene Glycol Bis(Allyl Carbonate) Monomer and CdS Nanoplates

[0204] Semi-conductive nanoparticles of formula CdS and having a shape of plate with length of 10 nm; width of 20 nm and thickness of 0.9 nm (corresponding to 3 monolayers) were prepared according to procedure disclosed in EP2633102.

[0205] 5 mL of a dispersion comprising CdS nanoplates were mixed with 2 mL of 3-mercaptoproprionic acid (MPA). This mixture was heated at 60 C. for 2 hours. Nanoplates were recovered by centrifugation and washed three times with ethanol and toluene. CdS nanoplates capped with MPA were redispersed in water at pH=10. This dispersion is called dispersion D1. Dispersion D1 had a weight content in nanoparticles of 0.5%. Nanoparticles of dispersion D1 were encapsulated according to the procedure disclosed in EP3630683 within a silica shell.

[0206] Table 4 below discloses the absorbance of dispersion D1.

TABLE-US-00004 TABLE 4 .sub.max 400 nm .sub.0.9 (at 0.9*A.sub.max) 402 nm .sub.0.5 (0.5*A.sub.max) 406 nm .sub.0.1 (0.1*A.sub.max) 410 nm |.sub.0.5 .sub.0.9| 4 nm |.sub.0.1 .sub.0.9| 8 nm

[0207] 10 mg of encapsulated CdS nanoplates of dispersion D1 were mixed with 1.65 mL of Diethylene glycol bis(allyl carbonate) and 100 mg of diisopropyl peroxydicarbonate (IPP) initiator. A homogeneous mixture is obtained by sonication in degassing mode at 25 C. for 60 seconds, yielding the polymerizable composition C1.

[0208] Polymerizable composition C1 was casted into moulds having centre thickness of 2 millimetres. The assembly was laid in an oven at 100 C. for 18 hours, then cooled and de-assembled, yielding plastic lens S1 of diameter about 2 cm.

[0209] Absorbance curves of CdS nanoplates in heptane (semi-dotted line), of CdS-MPA nanoparticles in water (dotted line) and of lens S1 (solid line) were measured as a function of light wavelength in the UV-visible and are shown on FIG. 3. A wavelength of transition .sub.max of 399 nm is obtained for lens S1.

[0210] Besides, the characteristics of lens S1 for 20.9, 20.5 and 20.1 are the same as the characteristics of dispersion of nanoparticles listed in table 4: incorporation of nanoparticles into polymerizable composition didn't change absorbance features

[0211] Lens S1 is a transparent lens, i.e. there is no observable scattering and an object can be recognized when observed through the lens. However, these lenses absorb very efficiently high energy visible light with a very sharp transition in absorbance curve.

Example 3: Ophthalmic Lens with Coatings Comprising ZnSe Nanospheres and Nanoplates

[0212] Semi-conductive nanoparticles of formula ZnSe and having a shape of sphere with diameter of 5.80.2 nm were prepared according to procedure known in the art and reported in New J. Chem., 2007, 31, 1843-1852.

[0213] 5 mL of a dispersion comprising ZnSe nanospheres were mixed with 5 mL of 3-mercaptoproprionic acid (MPA). This mixture was heated at 60 C. for 2 hours. The nanospheres were recovered by centrifugation and washed three times with absolute ethanol and toluene. ZnSe nanospheres capped with MPA were redispersed in water at pH=10. These nanospheres were encapsulated according to the procedure disclosed in EP3630683 within a silica shell and redispersed in 0.5 mL of methanol. This dispersion was called dispersion D2 and had a weight content of 2.5% of nanospheres.

[0214] Table 5 below discloses the absorbance of dispersion D2.

TABLE-US-00005 TABLE 5 .sub.max 424 nm .sub.0.9 (at 0.9*A.sub.max) 428 nm .sub.0.5 (0.5*A.sub.max) 432 nm .sub.0.1 (0.1*A.sub.max) 440 nm |.sub.0.5 .sub.0.9| 4 nm |.sub.0.1 .sub.0.9| 12 nm

[0215] Same experiment was reproduced with semi-conductive nanoparticles of formula ZnSe and having a shape of nanoplates with thickness of 1.9 nm (corresponding to 5 monolayers), length of 15 nm and width of 30 nm. These nanoplates were prepared according to procedure known by the man of the art and reported in Mater. Lett. 2013, 99, 172-175. ZnSe nanoplates were capped with MPA and were redispersed in water at pH=10. These nanoplates were encapsulated according to the procedure disclosed in EP3630683 within a silica shell and redispersed in 0.5 mL of methanol. This dispersion was called dispersion D3 and had a weight content of 2.5% of nanoplates.

[0216] In addition, a Sol-Gel solution SG was also prepared in a separated vial with 100 L of (3-Glycidyloxypropyl)trimethoxysilane, 65 L of diethoxydimethylsilane and 35 L of 0.1 M HCl. Solution SG was stirred for 24 hours at room temperature.

[0217] 50 L of dispersion D2 were added to 200 L of solution SG to obtain a polymerizable composition then deposited by spin coating on a glass lens at 400 rpm during 30 s (dispensing step) then 2000 rpm during 2 min (spreading step). The resulting lens S2 was then heated at 150 C. for 6 h in order to obtain a condensed 5 m thick Sol-Gel coating having a weight content in ZnSe nanospheres of 1% after curing.

[0218] Same experiment was reproduced with encapsulated ZnSe nanoplates. 50 L of dispersion D3 were added to 200 L of solution SG to obtain a polymerizable composition then deposited by spin coating on a glass lens at 400 rpm during 30 s (dispensing step) then 2000 rpm during 2 min (spreading step). The resulting lens S3 was then heated at 150 C. for 6 h in order to obtain a condensed 5 m thick Sol-Gel coating having a weight content in ZnSe nanoplates of 1% after curing.

[0219] Absorbance curves of ZnSe nanospheres in toluene (semi-dotted line), of encapsulated ZnSe nanospheres in methanol (dotted line) and of the coated glass lens S2 (solid line) were measured as a function of light wavelength in the UV-visible and are shown on FIG. 4.1. A wavelength of transition .sub.max of 410 nm is obtained for lens S2.

[0220] Besides, the characteristics of lens S2 for 20.9, 20.5 and 20.1 are the same as the characteristics of dispersion of nanoparticles listed in table 5: incorporation of nanoparticles in Sol-Gel coating didn't change absorbance features

[0221] Absorbance curves of ZnSe nanoplates in toluene (semi-dotted line), of encapsulated ZnSe nanoplates in methanol (dotted line) and of the coated glass lens S3 (solid line) were measured as a function of light wavelength in the UV-visible and are shown on FIG. 4.2. A wavelength of transition .sub.max of 401 nm is obtained for lens S3.

Example 4: Glass Container with a Light Filtering Material

[0222] All colorimetry measurements have been obtained after a measure of transmission followed by computation of colour. Transmission was measured with a JASCO UV-VIS770 spectrometer, with Xenon light source, for a range of wavelength from 380 nm to 780 nm. Spectrum of Illuminant D65 is defined in CIE standards.

[0223] Semi-conductive nanoparticles (hereafter NP6) of formula CdSe.sub.0.75S.sub.0.25 and having a shape of plate with length of 12 nm; width of 20 nm and thickness of 1.2 nm (corresponding to 4 monolayers) were prepared according to procedure disclosed in EP2633102. Nanoparticles NP6 were capped with a Poly(DHLA-co-PEGMEMA) copolymer to respectively prepare dispersions D4.

[0224] A commercial glass bottle B0 was used as glass container. The color of B0 is measured in L*a*b* color system: L*=86.3; a*=0.16 and b*=0.23. The commercial bottle B0 is dip-coated with dispersions D4, then heated at 150 C. for 6 h in order to obtain a condensed 5 m thick Sol-Gel coating having a weight content in nanoparticles NP6 of 1% after curing. Resulting coated bottle is B1.

[0225] FIG. 5 shows light transmission through bottles B0 as a control and B1. A.sub.max for bottle B1 is 480 nm.

[0226] A solution of Riboflavin at concentration of 250 mg.Math.L.sup.1 is prepared. This solution when measured in a 1 cm path light cuvette presents a maximum of absorbance at 442 nm with absorbance 1.03.

[0227] Bottle B0 was filled with the solution of Riboflavin and exposed to blue LED light exposure for 30 hours (emission spectrum of LED 430-465 nm, irradiance 0.1 W/cm.sup.2). Absorbance curves were recorded at different duration of blue light exposure for 0, 1, 4, 7, 12, 15, 24 and 30 hours. Absorbance at 442 nm is decreasing from 1.03 to 0.124 demonstrating that 88% Riboflavin has been photodegraded after 30 hours of blue light exposure.

[0228] The same experiment was reproduced using bottle B1. As a control, the same measurement was done in a bottle B0, without light exposure.

[0229] Table 6 below shows Riboflavine degradation and colorimetric properties of the bottles.

TABLE-US-00006 TABLE 6 .sub.max Lightness Luminous Bottle (nm) % degradation (variation from B0) Chroma transmission B0 NA 88 86.3 0.3 >95% B1 480 13 84.5 (1.8) 60 >95% B0 - No light NA <2% 86.3 (0) 0.3 NA

[0230] Table 6 demonstrates that degradation of Riboflavin contained in bottle B1 has been prevented thanks to light filtering material.

[0231] Lightness of glass bottle B1 is almost unchanged (from 86.3 to 84.5) and chroma is 60.

[0232] Finally, bottle B1 is a good light filtering glass container, providing protection against development of lightstruck flavour in beverages without degrading brightness of the glass container.

Example 5: Display Comprising a Light Filtering Material

[0233] 5 mL of a dispersion comprising ZnSe nanospheres NP5 were mixed with 5 mL of 3-mercaptoproprionic acid (MPA). This mixture was heated at 60 C. for 2 hours and then washed three times with absolute ethanol and toluene. ZnSe nanoparticles capped with MPA were redispersed in water at pH=10. These nanospheres were encapsulated according to the procedure disclosed in EP3630683 within a silica shell and redispersed in 0.5 mL of methanol. This dispersion D4 had a weight content of 2.5% of nanospheres.

[0234] In addition, a Sol-Gel solution SG was also prepared in a separated vial with 100 L of (3-Glycidyloxypropyl) trimethoxysilane, 65 L of diethoxydimethylsilane and 35 L of 0.1 M HCl. Solution SG was stirred for 24 hours at room temperature.

[0235] 50 L of dispersion D4 were added to 200 L of solution SG to obtain a polymerizable composition then deposited by spin coating on a glass protective layer of a standard LCD display at 400 rpm during 30 s (dispensing step) then 2000 rpm during 2 min (spreading step). The resulting layer L1 was then heated at 150 C. for 6 h in order to obtain a condensed 5 m thick Sol-Gel coating having a weight content in ZnSe nanospheres of 1% after curing. Thickness of layer L1 was adjusted to have an absorbance equal to 1 at max.

[0236] Layer L1 (6) was coated on the inner side of glass protective layer (55) and disposed in a display with a configuration shown on FIG. 6. In this display, light sources of image producing system comprises blue LED.

[0237] High energy blue light emitted by blue LED was very efficiently filtered out with layer L1 as the amount of light having a wavelength below 440 nm was dramatically decreased.

[0238] Table 7 below shows the amount of light filtered out for range of wavelength 400-440 nm (light to be filtered out) and range 440-500 nm (light to be maintained). Table 7 also shows the wavelength of maximum emission (nm). The characteristics of layer L1 for A.sub.max, .sub.0.9, .sub.0.5 and .sub.0.1 are the same as the characteristics of dispersion of nanoparticles listed in table 2: incorporation of nanoparticles in Sol-Gel coating didn't change absorbance features.

TABLE-US-00007 TABLE 7 400-440 nm (%) 440-500 nm (%) Peak (nm) Layer L1 87 13.6 447

[0239] Layer L1 is a good compromise to filter out high energy blue light without changing too much the emission peak of blue light, in particular the wavelength of maximum emission is not shifted and remains at 454 nm.

[0240] In this display, fluorescent materials are used to produce green and red light, from blue light emitted by blue LED. FIG. 8 shows intensity of white light emitted by display (Iin arbitrary unit) as a function of light wavelength (in nm) without light filtering material (L0) and with light filtering material L1.

[0241] Table 8 below shows coordinates of red, green, blue and white light emitted by this display, without light filtering material (L0) and with light filtering material L1, in the CIE Luv colour space. Taking for display without filter gamut G.sub.0 equal to 100, the gamut G.sub.1 of display with filter is 95.1.

TABLE-US-00008 TABLE 8 No filter Filter L1 Blue (0.15-0.05) (0.15-0.06) Green (0.31-0.63) (0.31-0.63) Red (0.65-0.35) (0.65-0.35) White point (0.33-0.33) (0.35-0.41)

[0242] In the CIE xyY color space, taking for display without filter gamut G.sub.0 equal to 100, the gamut G.sub.1 of display with filter is 97.4.

[0243] With filter L1, colour of white light has been slightly changed. However, colour of white light in such displays is defined by intensity of the three sources (red, green and blue). It is thus straightforward to increase intensity of blue source to restore a white light with coordinates of (0.33, 0.33) in CIE Luv. This adjustment has no effect on gamut.

[0244] Finally, filtering layer L1 demonstrates a very efficient compromise: emission of high energy blue light by display is strongly limited and ability to produce colours over a wide range is maintained.