Luminescent solar concentrator

Abstract

Luminescent solar concentrator (LSC) comprising an aqueous microemulsion including at least one photoluminescent compound. Said luminescent solar concentrator (LSC) can be advantageously used in solar devices (i.e. devices for exploiting solar energy) such as, for example, photovoltaic cells (or solar cells), photoelectrolytic cells. Said luminescent solar concentrator (LSC) can also be advantageously used in photovoltaic windows.

Claims

1. An aqueous microemulsion for a luminescent solar concentrator (LSC) comprising: from 20% by weight to 90% by weight of water with respect to the total weight of surfactant+co-surfactant+water; from 3% by weight to 25% by weight of at least one surfactant with respect to the total weight of surfactant+co-surfactant+water; from 6% by weight to 50% by weight of at least one co-surfactant with respect to the total weight of surfactant+co-surfactant+water; from 1% by weight to 90% by weight of at least one organic solvent immiscible with water with respect to the total weight of organic solvent immiscible with water+water; from 0.02% by weight to 2% by weight of at least one photoluminescent compound with respect to the total weight of photoluminescent compound+organic solvent immiscible with water.

2. The aqueous microemulsion according to claim 1, wherein said aqueous microemulsion comprises from 50% by weight to 70% by weight of water with respect to the total weight of surfactant+co-surfactant+water.

3. The aqueous microemulsion according to claim 1, wherein said aqueous microemulsion comprises from 10% by weight to 15% by weight of at least one surfactant with respect to the total weight of surfactant+co-surfactant+water.

4. The aqueous microemulsion according to claim 1, wherein said aqueous microemulsion comprises from 20% by weight to 30% by weight of at least one co-surfactant with respect to the total weight of surfactant+co-surfactant+water.

5. The aqueous microemulsion according to claim 1, wherein said aqueous microemulsion comprises from 5% by weight to 20% by weight of at least one organic solvent immiscible with water with respect to the total weight of organic solvent immiscible with water+water.

6. The aqueous microemulsion according to claim 1, wherein said aqueous microemulsion comprises from 0.1% by weight to 0.5% by weight of at least one photoluminescent compound with respect to the total weight of photoluminescent compound+organic solvent immiscible with water.

7. The aqueous microemulsion according to claim 1, wherein said photoluminescent compound is selected from benzothiadiazole compounds, acene compounds, or mixtures thereof, wherein said photoluminescent acene compounds absorb infrared radiation and are soluble and stable in the organic solvent immiscible with water.

8. The aqueous microemulsion according to claim 1, wherein said surfactant is selected from sodium dodecyl sulfate (SDS), sodium octadecyl sulfate, nonylphenol ether sulfate, or mixtures thereof.

9. The aqueous microemulsion according to claim 1, wherein said co-surfactant is selected from 1-butanol, 1-pentanol, 1-hexanol, 1-octanol, or mixtures thereof.

10. The aqueous microemulsion according to claim 1, wherein said organic solvent immiscible with water is selected from toluene, cyclohexane, heptane, or mixtures thereof.

11. A luminescent solar concentrator (LSC) comprising: a container including transparent walls; and at least one aqueous microemulsion according to claim 2 disposed in said container.

12. The luminescent solar concentrator (LSC) according to claim 11, wherein said transparent walls comprise at least one of alumina, titania, or mixtures thereof.

13. A solar device comprising at least one photovoltaic cell or at least one photoelectrolytic cell positioned on a luminescent solar concentrator (LSC) according to claim 11.

14. The luminescent solar concentrator (LSC) according to claim 11 wherein said transparent walls comprise silica.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The present invention will now be illustrated in greater detail by means of an embodiment with reference to FIGS. 1-3 provided hereunder.

(2) FIG. 1 represents a front view (1a) of a luminescent solar concentrator (LSC) (1) object of the present invention and a side view (1b) of a solar device (2) object of the present invention.

(3) FIG. 2 shows light intensity curves from a luminescent solar concentrator and attached photovoltaic cell, as described in Example 3.

(4) FIG. 3 shows effective power curves obtained from data from FIG. 2, as described in Example 3.

(5) With reference to the front view (1a) represented in FIG. 1, the luminescent solar concentrator (LSC) (1) comprises a cell for containing liquids (2) made of transparent walls (e.g., quartz), two holes on the upper side (not represented in FIG. 1) closed with two stoppers (3), an aqueous microemulsion including at least one photoluminescent compound [e.g., 4,7-di-2-thienyl-2,1,3-benzothiadiazole (DTB), or a mixture of 4,7-di-2-thienyl-2,1,3-benzothiadiazole (DTB) and 9,10-diphenylanthracene (DPA)](4), contained inside said cell (2).

(6) With reference to the side view (1b) represented in FIG. 1, the solar device (5) comprises a solar concentrator comprising a cell (2) made of transparent walls (e.g., quartz), two holes on the upper side (not represented in FIG. 1) closed with two stoppers (3) [only one stopper is visible in the side view (1b)], an aqueous microemulsion including at least one photoluminescent compound [e.g., 4,7-di-2-thienyl-2,1,3-benzothiadiazole (DTB), or a mixture of 4,7-di-2-thienyl-2,1,3-benzothiadiazole (DTB) and 9,10-diphenylanthracene (DPA)] (4), contained inside said cell (2), a photovoltaic cell (or solar cell) (6) [e.g., a silicon photovoltaic cell (or solar cell)] positioned on one of the sides of said cell (2), an ammeter (7) connected to said photovoltaic cell (or solar cell) (6).

(7) Some illustrative and non-limiting examples are provided hereinunder for a better understanding of the present invention and for its practical embodiment.

(8) In the following examples, the analytical techniques and characterization methods listed below, were used.

(9) Refraction Index (nD)

(10) The refraction index of the aqueous microemulsions including at least one photoluminescent compound obtained, was measured using an ATAGO RX7000CX refractometer, operating at 20° C. and a wavelength (A) equal to 589.3 nm [wavelength (A) of the inciding light of a sodium lamp (Na)].

(11) Micellar Radius (rm)

(12) The micellar radius of the aqueous microemulsions including at least one photoluminescent compound obtained, was measured using a Zeta sizer granulometer (PCS—Measurement angle 173°) on microemulsions filtered on a filter having a diameter equal to 0.22 μm.

(13) In the following examples: the 4,7-di-2-thienyl-2,1,3-benzothiadiazole (DTB) was synthesized as described in Example 1 of international patent application WO 2012/007834 in the name of the Applicant; the 9,10-diphenylanthracene (DPA) is of Sigma-Aldrich.

EXAMPLE 1

Preparation of Microemulsions Including 4,7-di-2-thienyl-2,1,3-benzothiadiazole (DTB)

(14) Microemulsions EM2-EM3-EM4-EM5-EM6-EM9-EM12-EM15

(15) 13 ml of an 0.6 M solution of sodium dodecyl sulfate (SDS) (Acros Organics 98%) in pure water MilliQ (MQ—Millipore) were poured into a 100 ml flask. 5.7 ml of 1-butanol (Acros Organics 99%) and a suitable volume (Vol..sub.sol.) of a solution of 4,7-di-2-thienyl-2,1,3-benzothiadiazole (DTB) in toluene (Carlo Erba) were subsequently added, in sequence, at a suitable concentration so as to obtain a concentration of 4,7-di-2-thienyl-2,1,3-benzothiadiazole in the microemulsion ([DTB].sub.microemuls.) equal to 2×10.sup.−3 M (EM2, EM3, EM4, EM5, EM6, EM12 and EM15), or equal to 3.3×10.sup.−4 M (EM9): the quantities of solution (Vol..sub.sol.), the concentration of 4,7-di-2-thienyl-2,1,3-benzothiadiazole (DTB.sub.conc.) and the concentration of 4,7-di-2-thienyl-2,1,3-benzo-thiadiazole in the microemulsion ([DTB].sub.microemuls.), are indicated in Table 1.

(16) The microemulsions obtained were subjected to measurements of the refraction index (nD) and of the micellar radius (rm) [the micellar radius (rm) was not measured in the case of the microemulsions EM2, EM3 and EM4] operating as described above: the data obtained are reported in Table 1.

(17) Microemulsions EM7-EM8

(18) 10 ml of an 0.95 M solution of sodium dodecyl sulfate (SDS) (Acros Organics 98%) in pure water MilliQ (MQ—Millipore) were poured into a 100 ml flask. 6.7 ml of 1-butanol (Acros Organics 99%) and a suitable volume (Vol..sub.sol.) of a solution of 4,7-di-2-thienyl-2,1,3-benzothiadiazole in toluene (Carlo Erba) were subsequently added, in sequence, at a suitable concentration so as to obtain a concentration of 4,7-di-2-thienyl-2,1,3-benzothiadiazole in the microemulsion ([DTB].sub.microemuls.) equal to 2×10.sup.−3 M: the quantities of solution (Vol..sub.sol.), the concentration of 4,7-di-2-thienyl-2,1,3-benzothiadiazole (DTB.sub.conc.) and the concentration of 4,7-di-2-thienyl-2,1,3-benzothiadiazole in the microemulsion ([DTB].sub.microemuls.), are reported in Table 1.

(19) The microemulsions obtained were subjected to measurements of the refraction index (nD) and of the micellar radius (rm) operating as described above: the data reported are indicated in Table 1.

EXAMPLE 2

Preparation of Microemulsions Including 4,7-di-2-thienyl-2,1,3-benzothiadiazole (DTB) and 9,10-diphenylanthracene (DPA)

(20) Microemulsions EM10-EM14

(21) 13 ml of an 0.6 M solution of sodium dodecyl sulfate (SDS) (Acros Organics 98%) in pure water MilliQ (MQ—Millipore) were poured into a 100 ml flask. 5.7 ml of 1-butanol (Acros Organics 99%) and a suitable volume (Vol..sub.sol.) of a solution of 4,7-di-2-thienyl-2,1,3-benzothiadiazole and 9,10-diphenylanthracene (DPA) in toluene (Carlo Erba) were subsequently added, in sequence, at a suitable concentration (DTB.sub.conc. and DPA.sub.conc.) so as to obtain a concentration of 4,7-di-2-thienyl-2,1,3-benzothiadiazole (DTB) in the microemulsion ([DTB].sub.microemuls.) equal to 1.8×10.sup.−3M and a concentration of 9,10-diphenylanthracene (DPA) in the microemulsion ([DPA].sub.microemuls.) equal to 1.8×10.sup.−3M: the quantities of solution (Vol..sub.sol.), the concentration of 4,7-di-2-thienyl-2,1,3-benzothiadiazole (DTB.sub.conc.) and 9,10-diphenylanthracene (DPA.sub.conc.), and the concentration of 4,7-di-2-thienyl-2,1,3-benzo-thiadiazole ([DTB].sub.microemuls.) and 9,10-diphenylanthracene ([DPA].sub.microemuls.) in the microemulsion, are reported in Table 2.

(22) The microemulsions obtained were subjected to measurements of the refraction index (nD) and of the micellar radius (rm) operating as described above: the data obtained are reported in Table 2.

EXAMPLE 3

(23) Power Measurements (P.sub.max)

(24) The power measurements of the microemulsions obtained as described above in Example 1 and in Example 2, were carried out using a Hellma quartz cuvette having dimensions of 10 cm×10 cm×0.6 cm (optical path: 1 mm) filled with 8.1 ml of the microemulsion to be analyzed. A photovoltaic cell IXYS-XOD17 having a surface of 1.2 cm.sup.2 connected to an ammeter was applied on an edge of the cuvette.

(25) The surface of the cuvette was then illuminated, with a light source using an ABET solar simulator mod. SUN 2000 equipped with a 550 Watt OF Xenon lamp having a power equal to 1 sun (1000 W/m.sup.2), for 10 seconds. A first measurement was carried out, illuminating the whole cuvette (10 cm×10 cm) and the electric power generated due to the illumination, was measured.

(26) Power measurements were then carried out, by covering surfaces of the cuvette having a variable area, with an opaque coating (masking), at an increasing distance from the edge on which the photovoltaic cell was fixed (total of 11 measurements). These measurements, carried out under variable shielding conditions, allow the contribution of possible waveguide, edge or multiple diffusion effects due to the support, to be quantified and then subtracted.

(27) The light intensity curve (measured in ampere)−current produced (measured in volts) (curves I-V indicated in FIG. 2) was registered for each portion of cuvette illuminated, and the effective power of the photovoltaic cell was calculated from this (curves indicated in FIG. 3): the effective power (P.sub.max) was subsequently normalized per cm.sup.2 of surface illuminated and the values obtained are reported in Table 1 and Table 2.

(28) TABLE-US-00001 TABLE 1 (Vol..sub.sol.) (DTB.sub.conc.) (DTB.sub.microemuls.) P.sub.max rm Microemulsion (ml) (M) (M) nD (mW/cm.sup.2) (nm) EM2 3.7 0.010 2 × 10.sup.−3 1.385 0.065 — EM3 1.0 0.040 2 × 10.sup.−3 1.374 0.056 — EM4 3.7 0.010 2 × 10.sup.−3 1.388 0.067 — 1.386.sup.(a) EM5 3.7 0.010 2 × 10.sup.−3 1.388 0.068 3.62 ± 0.02 1.3865.sup.(b) EM6 1.0 0.040 2 × 10.sup.−3 1.374 0.044 2.10 ± 0.01 EM7 1.3 0.028 2 × 10.sup.−3 1.386 0.061 4.65 ± 0.07 EM8 7.7 0.0063 2 × 10.sup.−3 1.414 0.075 2.45 ± 0.02 EM9 3.7 0.002 3.3 × 10.sup.−4   1.3875 0.043 3.50 ± 0.03 EM12 1.9 0.02 2 × 10.sup.−3 1.378 0.057 2.60 ± 0.1  EM15 4.2 0.01 2 × 10.sup.−3 1.390 0.064 5.6 ± 0.3 .sup.(a)refraction index (nD) measured after 5 months; .sup.(b)refraction index (nD) measured after 2 months.

(29) TABLE-US-00002 TABLE 2 Micro- (Vol..sub.sol.) (DTB.sub.conc.) (DTB.sub.microemuls.) (DPA.sub.conc.) (DPA.sub.microemuls.) P.sub.max rm emulsion (ml) (M) (M) (M) (M) nD (mW/cm.sup.2) (nm) EM10 4.2 0.010 1.8 × 10.sup.−3 0.010 1.8 × 10.sup.−3 1.389 0.070 3.58 ± 0.01 EM14 4.2 0.010 1.8 × 10.sup.−3 0.010 1.8 × 10.sup.−3 1.390 0.071 4.42 ± 0.08