Luminescent solar concentrator

Abstract

Luminescent solar concentrator (LSC) comprising at least one solution including at least one photoluminescent compound and at least one polyether polyol. Said luminescent solar concentrator (LSC) can be advantageously used in photovoltaic devices (or solar devices) such as, for example, photovoltaic cells (or solar cells), photoelectrolytic cells. In addition, said luminescent solar concentrator (LSC) can be advantageously used in photovoltaic windows.

Claims

1. Luminescent solar concentrator (LSC) comprising at least one liquid solution including at least one photoluminescent compound and at least one polyether polyol, wherein the at least one photoluminescent compound is selected from the group consisting of perylene compounds, benzothiadiazole compounds, distributed benzoheterodiazole compounds, distributed diaryloxybenzoheterodiazole compounds, and combinations thereof.

2. Luminescent solar concentrator (LSC) according to claim 1, wherein said photoluminescent compound is present in said solution in a molar concentration ranging from 1×10.sup.−4 M to 3×10.sup.−3 M.

3. Luminescent solar concentrator (LSC) according to claim 1, wherein said polyether polyol is selected from polyethylene glycols having a number average molecular weight (Mn) ranging from 150 daltons to 600 daltons, or mixtures thereof; polypropylene glycols having a number average molecular weight (Mn) ranging from 250 daltons to 4000 daltons, or mixtures thereof; or mixtures thereof.

4. Photovoltaic device (or solar device) comprising at least one photovoltaic cell (or solar cell) or at least one photoelectrolytic cell placed on the edges of at least one luminescent solar concentrator (LSC) according to claim 1.

5. Photovoltaic window comprising at least one photovoltaic cell (or solar cell) or at least one photoelectrolytic cell placed on the edges of at least one luminescent solar concentrator (LSC) according to claim 1.

6. Luminescent solar concentrator (LSC) according to claim 1, wherein said photoluminescent compound is present in said solution in a molar concentration ranging from 0.5×10.sup.−3 M to 2×10.sup.−3 M.

7. Luminescent solar concentrator (LSC) comprising: a cell for liquids of a transparent material, said cell having four sides and being provided with at least one hole on at least one of the four sides; at least one liquid solution including at least one photoluminescent compound selected from the group consisting of perylene compounds, benzothiadiazole compounds, distributed benzoheterodiazole compounds, distributed diaryloxybenzoheterodiazole compounds, and combinations thereof and at least one polyether polyol contained within said cell for liquids, wherein said photoluminescent compound is present in said solution in a molar concentration ranging from 1×10.sup.−4 M to 3×10.sup.−3 M.

8. Luminescent solar concentrator (LSC) according to claim 7, wherein said transparent material is selected from transparent glass such as silica, quartz, alumina, titania, or mixtures thereof.

9. Luminescent solar concentrator (LSC) according to claim 7, wherein said polyether polyol is selected from polyethylene glycols having a number average molecular weight (Mn) ranging from 150 daltons to 600 daltons, or mixtures thereof; polypropylene glycols having a number average molecular weight (Mn) ranging from 250 daltons to 4000 daltons, or mixtures thereof; or mixtures thereof.

10. Photovoltaic device (or solar device) comprising at least one photovoltaic cell (or solar cell) or at least one photoelectrolytic cell placed on the edges of at least one luminescent solar concentrator (LSC) according to claim 9.

11. Luminescent solar concentrator (LSC) according to claim 7, wherein said transparent material is selected from transparent glass such as silica, quartz, alumina, titania, or mixtures thereof; wherein said photoluminescent compound is present in said solution in a molar concentration ranging from 0.5×10.sup.−3 M to 2×10.sup.−3 M wherein said polyether polyol is selected from polyethylene glycols having a number average molecular weight (Mn) ranging from 150 daltons to 600 daltons, or mixtures thereof; polypropylene glycols having a number average molecular weight (Mn) ranging from 250 daltons to 4000 daltons, or mixtures thereof; or mixtures thereof.

Description

EXAMPLE 1 (COMPARATIVE)

(1) Preparation of Solutions of a Photoluminescent Compound in Toluene

(2) DTB/Toluene Solution (Ref. 1)

(3) 22 mg of 4,7-di-2-thienyl-2,1,3-benzothiadiazole (DTB) and 72.9 ml of toluene (Aldrich) were placed in a 100 ml flask: the whole was left, under stirring, at room temperature (25° C.), for about 15 minutes, obtaining a yellow solution having a concentration of 4,7-di-2-thienyl-2,1,3-benzothiadiazole (BTD) in the solution equal to 1×10.sup.−3 M.

(4) (MPDTBOP)/Toluene Solution (Ref. 2)

(5) 10.4 mg of 5,6-diphenoxy-4,7-bis[5-(2,6-dimethylphenyl)-2-thienyl]benzo[c]1,2,5-thiadiazole (MPDTBOP) and 15.1 ml of toluene (Aldrich) were placed in a 50 ml flask: the whole was left, under stirring, at room temperature (25° C.), for about 15 minutes, obtaining a yellow solution having a concentration of (MPDTBOP) in the solution equal to 1×10.sup.−3 M.

(6) Lumogen® F Red 305/Toluene Solution (Ref. 3)

(7) 6.6 ml of a Lumogen® F Red 305/toluene solution at 2×10.sup.−3 M concentration (previously prepared by dissolving 50.3 mg of Lumogen® F Red 305 in 23.2 ml of toluene, under stirring, at room temperature (25° C.), for about 15 minutes) and 6.6 ml of toluene (Aldrich) were placed in a 50 ml flask, obtaining a red solution having a concentration of Lumogen® F Red 305 in the solution equal to 1×10.sup.−3 M.

EXAMPLE 2 (INVENTION)

(8) Preparation of Solutions of a Photoluminescent Compound in Polyethylene Glycols

(9) DTB/PEG 200 Solution (PEG8)

(10) 8.9 mg of 4,7-di-2-thienyl-2,1,3-benzothiadiazole (DTB) and 30.3 ml of polyethylene glycol (M.sub.n=200) (PEG 200) (Sigma-Aldrich) were placed in a 50 ml flask: the whole was left, under stirring, at room temperature (25° C.), for about 20 minutes, obtaining an orange solution having a concentration of 4,7-di-2-thienyl-2,1,3-benzothiadiazole (BTD) in the solution equal to 1×10.sup.−3 M.

(11) DTB/PEG 400 Solution (PEG9)

(12) 9.5 mg of 4,7-di-2-thienyl-2,1,3-benzothiadiazole (DTB) and 31.6 ml of polyethylene glycol (M.sub.n=400) (PEG 400) (Sigma-Aldrich) were placed in a 50 ml flask: the whole was left, under stirring, at room temperature (25° C.), for about 30 minutes, obtaining an orange solution having a concentration of 4,7-di-2-thienyl-2,1,3-benzothiadiazole (BTD) in the solution equal to 1×10.sup.−3 M.

(13) (MPDTBOP)/PEG400 Solution (PEG10)

(14) 18.5 mg of 5,6-diphenoxy-4,7-bis[5-(2,6-dimethylphenyl)-2-thienyl]benzo[c]1,2,5-thiadiazole (MPDTBOP) and 26.9 ml polyethylene glycol (M.sub.n=400) (PEG 400) (Sigma-Aldrich) were placed in a 50 ml flask: the whole was left, under stirring, at 40° C., for about 60 minutes, obtaining a yellow-orange solution having a concentration of (MPDTBOP) in the solution equal to 1×10.sup.−3 M.

(15) Lumogen® F Red 305/PEG400 Solution (PEG11)

(16) 29.5 mg of Lumogen® F Red 305 (BASF) and 27.4 ml of polyethylene glycol (M.sub.n=400) (PEG 400) (Sigma-Aldrich) were placed in a 50 ml flask: the whole was left, under stirring, at 40° C., for about 60 minutes, obtaining a red solution having a Lumogen® F Red 305 concentration in the solution equal to 1×10.sup.−3 M.

EXAMPLE 3 (INVENTION)

(17) Preparation of Solutions of a Photoluminescent Compound in Polypropylene Glycols

(18) DTB/PPG425 Solution (PPG3)

(19) 11.1 mg of 4,7-di-2-thienyl-2,1,3-benzothiadiazole (DTB) and 26.9 ml of polypropylene glycol (M.sub.n=425) (PPG 425) (Sigma-Aldrich) were placed in a flask of 50 ml: the whole was left, under stirring, at room temperature (25° C.), for about 40 minutes, obtaining a yellow solution having a concentration of 4,7-di-2-thienyl-2,1,3-benzothiadiazole (BTD) in the solution equal to 1×10.sup.−3 M.

(20) (MPDTBOP)/PPG425 Solution (PPG1)

(21) 18.4 mg of 5,6-diphenoxy-4,7-bis[5-(2,6-dimethylphenyl)-2-thienyl]benzo [c]1,2,5-thiadiazole (MPDTBOP) and 26.8 ml of polypropylene glycol (M.sub.n=425) (PPG 425) (Sigma-Aldrich) were placed in a 50 ml flask: the whole was left, under stirring, at 40° C., for about 60 minutes, obtaining a yellow solution having a concentration of (MPDTBOP) in the solution equal to 1×10.sup.−3 M.

(22) Lumogen® F Red 305/PPG425 Solution (PPG2)

(23) 27 mg of Lumogen® F Red 305 (BASF) and 25 ml of polypropylene glycol (M.sub.n=425) (Sigma-Aldrich) were placed in a 50 ml flask: the whole was left, under stirring, at 40° C., for about 60 minutes, obtaining a red solution having a concentration of Lumogen® F Red 305 in the solution equal to 1×10.sup.−3 M.

(24) (MPDTBOP)/PPG2700 Solution (PPG4)

(25) 19.8 mg of 5,6-diphenoxy-4,7-bis[5-(2,6-dimethylphenyl)-2-thienyl]benzo[c]1,2,5-thiadiazole (MPDTBOP) and 28.6 ml of polypropylene glycol (M.sub.n=2700) (PPG 2700) (Sigma-Aldrich) were placed in a 50 ml flask: the whole was left, under stirring, at 40° C., for about 60 minutes, obtaining a yellow solution having a concentration of (MPDTBOP) in the solution equal to 1×10.sup.−3 M.

(26) Lumogen® F Red 305/PPG2700 Solution (PPG5)

(27) 27 mg of Lumogen® F Red 305 (BASF) and 25.4 ml of polypropylene glycol (M.sub.n=2700) (Sigma-Aldrich) were placed in a 50 ml flask: the whole was left, under stirring, at 40° C., for about 60 minutes, obtaining a yellow solution having a concentration of Lumogen® F Red 305 in the solution equal to 1×10.sup.−3 M.

EXAMPLE 4

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

(29) The power measurements of some of the solutions obtained as described above in Example 1 (comparative), in Example 2 (invention) and in Example 3 (invention), were carried out by 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 solution to be analysed. A IXYS-XOD17 photovoltaic cell having an area of 1.2 cm.sup.2 connected to an ammeter was applied to one cuvette edge.

(30) The surface of the cuvette was then illuminated with a light source using an ABET solar simulator mod. SUN 2000 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 made illuminating the whole cuvette (10 cm×10 cm) and the electric power generated by the effect of the illumination was measured.

(31) Subsequently, power measurements were carried out covering surfaces of the cuvette having a variable area with a opaque coating (mask), at a distance increasing from the edge on which the photovoltaic cell was fixed (total 10 measurements). Subsequently, a last measurement was made on an illuminated surface area of 1 cm×10 cm located on the opposite side to the edge on which the photovoltaic cell was fixed. These measurements, under variable shielding conditions, allow the contribution of optional waveguide, edge or multiple diffusion effects due to the support to be quantified and then removed.

(32) For each portion of the illuminated cuvette, the light intensity curve (measured in amperes)− current produced (measured in volt) (IN curves shown in FIG. 2) was recorded and from this the effective power of the photovoltaic cell (curves shown in FIG. 3) was calculated: the maximum effective power (P.sub.max) was subsequently normalised per cm.sup.2 of illuminated surface.

(33) Table 1 shows the average effective maximum power values (P.sub.max average) which is obtained from the average of all effective power values (P.sub.max) normalized per cm.sup.2 of illuminated surface, calculated for each portion of illuminated cuvette, omitting the first and last measurement relative to the portion of the cuvette containing the edge with the photovoltaic cell and the opposite edge, respectively.

(34) TABLE-US-00001 TABLE 1 PHOTOLUMINESCENT P.sub.max average SAMPLE COMPOUND SOLVENT (mW/cm.sup.2) Ref. 1 DTB toluene 0.038 Ref. 2 MPDTBOP toluene 0.054 Ref. 3 F305 toluene 0.067 PEG8 DTB PEG200 0.034 PEG9 DTB PEG400 0.036 PEG10 MPDTBOP PEG400 0.050 PEG11 F305 PEG400 0.035 PPG1 MPDTBOP PPG425 0.048 PPG2 F305 PPG425 0.062 PPG3 DTB PPG425 0.037

(35) From the data shown in Table 1 it is deduced that: in the case of 4,7-di-2-thienyl-2,1,3-benzothiadiazole (DTB) and of 5,6-diphenoxy-4,7-bis[5-(2,6-dimethylphenyl)-2-thienyl]benzo[c]1,2,5-thiadiazole (MPDTBOP), the devices comprising the solutions object of the present invention (PEG8, PEG9, PEG10, PPG1 and PPG3) exhibit an efficiency, in terms of the average effective maximum power (P.sub.max average), comparable to that of devices comprising the known solutions (Ref. 1 and Ref. 2); in the case of Lumogen® F Red 305, the device comprising the solution of the present invention (PEG11) shows an efficiency, in terms of the average effective maximum power (P.sub.max average), good but lower than that of the device comprising the known solution (Ref. 3); the device comprising the solution object of the present invention (PPG2) exhibits an efficiency, in terms of the average effective maximum power (P.sub.max average), comparable to that of the device comprising the known solution (Ref. 3).

EXAMPLE 5

(36) Measures of Photostability

(37) The PPG1 and PPG4 solutions were diluted with the same solvent present in them in order to obtain a concentration of the photoluminescent compound present equal to 1×10.sup.−5 M, obtaining the following PPG1a and PPG4a solutions.

(38) The above mentioned solutions were subjected to UV-visible spectroscopy by operating as follows. Each solution was poured into a vial of about 20 ml with a screw cap up to ⅔ of the volume and aged under continuous lighting in an Atlas XenoTest Beta+ device according to DIN EN ISO 4892-2:2013 procedure. After 24 hours of aging, the vials were removed and the solutions were subjected to UV-visible spectroscopy in order to obtain the amount of photoluminescent compound still present. The UV-Vis spectra were recorded with a double beam spectrophotometer and a double Perkin Elmer Lambda 950 monochromator.

(39) In the solutions subjected to accelerated aging the UV-Vis absorption spectrophotometry allowed the monitoring of the absorbance decrease in the visible region by measuring the relative absorbance in percent (A %) defined as (At)/(A0), that is, as the ratio between the absorbance at time t (At) and the absorbance at time 0 (A0).

(40) Table 2 shows the relative absorbance values in percent (A %) [(At)/(A0)] after 24 hours of aging.

(41) TABLE-US-00002 TABLE 2 PHOTOLUMINESCENT SAMPLE COMPOUND SOLVENT (A %) [(At)/(A0)] PPG1a MPDTBOP PPG425 82 PPG4a MPDTBOP PPG2700 100

(42) From the data shown in Table 2 it is deduced that the solutions object of the present invention (PPG1a and PPG3a) have good stability.