Disubstituted diaryloxybenzoheterodiazole compounds

Abstract

Disubstituted diaryloxybenzoheterodiazole compound of general formula (1): in which:—Z represents a sulfur atom, an oxygen atom, a selenium atom; or an NR.sub.5 group in which R.sub.5 is selected from linear or branched C.sub.1-C.sub.20, preferably C.sub.1-C.sub.8, alkyl groups, or from optionally substituted aryl groups;—R.sub.1, R.sub.2 and R.sub.3 are as defined in the claims. The said disubstituted diaryloxybenzoheterodiazole compound of general formula (I) can advantageously be used as a spectrum converter in luminescent solar concentrators (LSCs) which are in turn capable of improving the performance of photovoltaic devices (or solar devices) selected, for example, from photovoltaic cells (or solar cells), photovoltaic modules (or solar modules) on either a rigid substrate or a flexible substrate. ##STR00001##

Claims

1. Luminescent solar concentrator (LSC) including at least one disubstituted diaryloxybenzoheterodiazole compound of general formula (I): ##STR00029## in which: Z represents a sulfur atom, an oxygen atom, a selenium atom; or an NR.sub.5 group in which R.sub.5 is selected from linear or branched C.sub.1-C.sub.20 alkyl groups, or from optionally substituted aryl groups; R.sub.1, R.sub.2 and R.sub.3, which are the same or different, represent a hydrogen atom; or are selected from linear or branched C.sub.1-C.sub.20 alkyl groups; linear or branched C.sub.1-C.sub.20 alkyl groups containing heteroatoms; optionally substituted cycloalkyl groups; optionally substituted aryl groups; optionally substituted linear or branched C.sub.1-C.sub.20alkoxyl groups; optionally substituted phenoxyl groups, or —OCOR.sub.6 groups in which R.sub.6 is selected from linear or branched C.sub.1-C.sub.20 alkyl groups, or is a cyano group; wherein said optionally substituted aryl group of R.sub.1 is selected from optionally substituted phenyl, naphthyl, phenylnaphthyl, phenanthrene or anthracene; or R.sub.1 and R.sub.2, can optionally be linked together so as to form, together with the carbon atoms to which they are linked, a saturated, unsaturated or aromatic cyclic ring or a polycyclic system containing from 3 to 14 carbon atoms, optionally containing one or more heteroatoms; or R.sub.2 and R.sub.3 can optionally be linked together so as to form, together with the carbon atoms to which they are linked, a saturated, unsaturated or aromatic cyclic ring or a polycyclic system containing from 3 to 14 carbon atoms, optionally containing one or more heteroatoms; R.sub.4, which are the same or different, are selected from optionally substituted aryl groups.

2. Luminescent solar concentrator (LSC) according to claim 1, wherein in said general formula (I): Z represents a sulfur atom; R.sub.1, which are the same, represent a hydrogen atom; or are selected from optionally substituted phenyl groups; R.sub.2 and R.sub.3, which are the same, represent a hydrogen atom; R.sub.4, which are the same, are selected from optionally substituted aryl groups.

3. Photovoltaic device comprising at least one photovoltaic cell, and at least one luminescent solar concentrator (LSC) according to claim 1.

4. Luminescent solar concentrator (LSC) according to claim 1 wherein in R.sub.1 said optionally substituted phenyl group is selected from methylphenyl, dimethylphenyl, trimethylphenyl, di-iso-propylphenyl, t-butylphenyl, methoxyphenyl, hydroxyphenyl, phenyloxyphenyl, fluorophenyl, pentafluorophenyl, chlorophenyl, nitrophenyl or dimethylaminophenyl.

5. Luminescent solar concentrator (LSC) according to claim 4 wherein in R.sub.4 said optionally substituted aryl groups are selected from phenyl, t-butylphenyl, naphthyl, dimethylphenyl or diphenyl.

Description

EXAMPLE 1

Synthesis of 5,6diphenoxy-4,7-bis(2-thienyl)-2,1,3-benzothiadiazole of formula (Ia)

(1) ##STR00019##

(2) In a 100 ml flask, fitted with a magnetic stirrer, thermometer and condenser, in inert atmosphere, phenol (Aldrich) (742 mg; 7.9 mmoles) and potassium carbonate (Aldrich) (700 mg; 5.1 mmoles) were added to a suspension of 5,6-difluoro-4,7-bis(2-thienyl)-2,1,3-benzothiadiazole (Sunatech) (630 mg; 1.9 mmoles) in N,N-dimethylformamide (Aldrich) (6 ml): the reaction mixture obtained was heated to 92° C. and held at that temperature, with stirring, for 12 hours. Subsequently, after 20 ml of distilled water had been added, there was obtained a precipitate which was recovered by filtration and washed with distilled water (30 ml), obtaining 865 mg of 5,6-diphenoxy-4,7-bis(2-thienyl)-2,1,3-benzothiadiazole of formula (Ia) [DTB(OPh).sub.2] (yield=94%).

EXAMPLE 2

Synthesis of 5,6-di(4-t-butylphenoxy)-4,7-bis(2-thienyl)-2,1,3-benzothiadiazole of formula (Ib)

(3) ##STR00020##

(4) In a 100 ml flask, fitted with a magnetic stirrer, thermometer and condenser, in inert atmosphere, 4-t-butylphenol (Aldrich) (1.2 g; 7.9 mmoles) and potassium carbonate (Aldrich) (700 mg; 5.1 mmoles) were added to a suspension of 5,6-difluoro-4,7-bis(2-thienyl)-2,1,3-benzothiadiazole (Sunatech) (630 mg; 1.9 mmoles) in N,N-dimethylformamide (Aldrich) (6 ml): the reaction mixture obtained was heated to 92° C. and held at that temperature, with stirring, for 12 hours. Subsequently, after 20 ml of distilled water had been added, there was obtained a precipitate which was recovered by filtration, washed with distilled water (30 ml), and purified by elution in a silica gel chromatography column [eluent: mixture of n-heptane (Aldrich)/ethyl acetate (Aldrich) in a ratio of 9/1 (v/v)], obtaining 1 g of 5,6-di(4-t-butylphenoxy)-4,7-bis(2-thienyl)-2,1,3-benzothiadiazole of formula (Ib) [DTB(OPhBu.sup.t).sub.2] (yield=88%).

EXAMPLE 3

Synthesis of 5,6-di(2-naphthoxy)-4,7-bis(2-thienyl)-2,1,3-benzothiadiazole of formula (Ic)

(5) ##STR00021##

(6) In a 100 ml flask, fitted with a magnetic stirrer, thermometer and condenser, in inert atmosphere, 2-naphthol (Aldrich) (300 mg; 2.08 mmoles) and potassium carbonate (Aldrich) (290 mg; 2.1 mmoles) were added to a suspension of 5,6-difluoro-4,7-bis(2-thienyl)-2,1,3-benzothiadiazole (Sunatech) (160 mg; 0.48 mmoles) in N,N-dimethylformamide (Aldrich) (2 ml): the reaction mixture obtained was heated to 92° C. and held at that temperature, with stirring, for 12 hours. Subsequently, after 10 ml of distilled water had been added, there was obtained a precipitate which was recovered by filtration, washed with distilled water (15 ml), and purified by elution in a silica gel chromatography column [eluent: mixture of n-heptane (Aldrich)/ethyl acetate (Aldrich) in a ratio of 85/15 (v/v)], obtaining 220 mg of 5,6-di(2-naphthoxy)-4,7-bis(2-thienyl)-2,1,3-benzothiadiazole of formula (Ic) [DTB(O-2-Naph).sub.2] (yield=75%).

EXAMPLE 4

Synthesis of 5,6-di(4-phenylphenoxy)-4,7-bis(2-thienyl)-2,1,3-benzothiadiazole of formula (Id)

(7) ##STR00022##

(8) In a 100 ml flask, fitted with a magnetic stirrer, thermometer and condenser, in inert atmosphere, 4-phenylphenol (Aldrich) (300 mg; 2.08 mmoles) and potassium carbonate (Aldrich) (290 mg; 2.1 mmoles) were added to a suspension of 5,6-difluoro-4,7-bis(2-thienyl)-2,1,3-benzothiadiazole (Sunatech) (160 mg; 0.48 mmoles) in N,N-dimethylformamide (Aldrich) (2 ml): the reaction mixture obtained was heated to 92° C. and held at that temperature, with stirring, for 12 hours. Subsequently, after 10 ml of distilled water had been added, there was obtained a precipitate which was recovered by filtration, washed with distilled water (15 ml), and purified by elution in a silica gel chromatography column [eluent: mixture of n-heptane (Aldrich)/dichloromethane (Aldrich) in a ratio of 95/5 (v/v)], obtaining 230 mg of 5,6-di(4-phenylphenoxy)-4,7-bis(2-thienyl)-2,1,3-benzothiadiazole of formula (Id) [DTB(OBPh).sub.2] (yield=75%).

EXAMPLE 5

Synthesis of 5,6-di(2,6-dimethylphenoxy)-4,7-bis(2-thienyl)-2,1,3-benzothiadiazole of formula (Ie)

(9) ##STR00023##

(10) In a 100 ml flask, fitted with a magnetic stirrer, thermometer and condenser, in inert atmosphere, 2,6-dimethylphenol (Aldrich) (253 mg; 2.08 mmoles) and potassium carbonate (Aldrich) (290 mg; 2.1 mmoles) were added to a suspension of 5,6-difluoro-4,7-bis(2-thienyl)-2,1,3-benzothiadiazole (Sunatech) (160 mg; 0.48 mmoles) in N,N-dimethylformamide (Aldrich) (2 ml): the reaction mixture obtained was heated to 92° C. and held at that temperature, with stirring, for 12 hours. Subsequently, after 20 ml of distilled water had been added, there was obtained a precipitate which was recovered by filtration, washed with distilled water (15 ml), and purified by elution in a silica gel chromatography column [eluent: mixture of n-heptane (Aldrich)/dichloromethane (Aldrich) in a ratio of 85/15 (v/v)], obtaining 230 mg of 5,6-di(2,6-dimethylphenoxy)-4,7-bis(2-thienyl)-2,1,3-benzothiadiazole of formula (Ie) [DTB(OPh-2,6-Me.sub.2).sub.2] (yield=81%).

EXAMPLE 6

Synthesis of 5,6-diphenoxy-4,7-bis(5-bromo-2-thienyl)-2,1,3-benzothiadiazole of formula (a)

(11) ##STR00024##

(12) In a 100 ml flask, fitted with a magnetic stirrer, thermometer and condenser, in inert atmosphere, N-bromosuccinimide (Aldrich) (665.3 mg; 3.8 mmoles) was added to a suspension of 5,6-diphenoxy-4,7-bis(2-thienyl)-2,1,3-benzothiadiazole of formula (Ia) obtained as described in Example 1 (865 mg; 1.8 mmoles) in tetrahydrofuran (Aldrich) (10 ml): the reaction mixture obtained was left in the dark, with stirring, at ambient temperature (25° C.), for 12 hours. Subsequently, after 20 ml of distilled water had been added, there was obtained a precipitate which was recovered by filtration and washed with distilled water (30 ml), obtaining 1 g of 5,6-diphenoxy-4,7-bis(5-bromo-2-thienyl)-2,1,3-benzothiadiazole of formula (a) (yield=90%).

EXAMPLE 7

Synthesis of 5,6-diphenoxy-4,7-bis[5-(2,6-dimethylphenyl)-2-thienyl]benzo[c]1,2,5-thiadiazole of formula (If)

(13) ##STR00025##

(14) In a 100 ml flask, fitted with a magnetic stirrer, thermometer and condenser, in inert atmosphere, 2,6-dimethylphenylboronic acid (Aldrich) (158 mg; 1.05 mmoles) and an aqueous solution of 2.17 M of potassium carbonate (Aldrich) (480 mg in 1.6 ml of water; 3.47 mmoles) were added to a solution of 5,6-diphenoxy-4,7-bis(5-bromo-2-thienyl)-2,1,3-benzothiadiazole of formula (a) obtained as described in Example 6 (270 mg; 0.4 mmoles) in 1,4-dioxane (Aldrich) (5 ml). After having removed the air present by means of 3 vacuum/nitrogen cycles, palladium-tetrakistriphenylphosphine (Aldrich) (22 mg; 0.02 mmoles) was added, obtaining a reaction mixture which was heated to 95° C. and held at the said temperature, with stirring, for 14 hours. The reaction mixture was then poured into distilled water (50 ml) and extracted with dichloromethane (Aldrich) (3×25 ml). The organic phase obtained was washed to neutral with distilled water (3×25 ml), and then dried over sodium sulfate (Aldrich). The residual solvent was removed by distillation at reduced pressure. The residue obtained was purified by elution in a silica gel chromatography column [eluent: mixture of n-heptane (Aldrich)/dichloromethane (Aldrich) in a ratio of 9/1 (v/v)], obtaining 250 mg of 5,6-diphenoxy-4,7-bis[5-(2,6-dimethylphenyl)-2-thienyl]benzo[c]1,2,5-thiadiazole of formula (If) [5-(2,6-Me.sub.2Ph).sub.2DTB(OPh).sub.2] (yield=90%).

EXAMPLE 8

Synthesis of 5,6-diphenoxy-4,7-bis[5-(2,5-dimethylphenyl)-2-thienyl]benzo[c]1,2,5-thiadiazole of formula (Ig)

(15) ##STR00026##

(16) In a 100 ml flask, fitted with a magnetic stirrer, thermometer and condenser, in inert atmosphere, 2,5-dimethylphenylboronic acid (Aldrich) (158 mg; 1.05 mmoles) and an aqueous solution of 2.17 M of potassium carbonate (Aldrich) (480 mg in 1.6 ml of water; 3.47 mmoles) were added to a solution of 5,6-diphenoxy-4,7-bis(5-bromo-2-thienyl)-2,1,3-benzothiadiazole of formula (a) obtained as described in Example 6 (270 mg; 0.4 mmoles) in 1,4-dioxane (Aldrich) (5 ml). After having removed the air present by means of 3 vacuum/nitrogen cycles, palladium-tetrakistriphenylphosphine (Aldrich) (22 mg; 0.02 mmoles) was added, obtaining a reaction mixture which was heated to 95° C. and held at the said temperature, with stirring, for 14 hours. The reaction mixture was then poured into distilled water (50 ml) and extracted with dichloromethane (Aldrich) (3×25 ml). The organic phase obtained was washed to neutral with distilled water (3×25 ml) and then dried over sodium sulfate (Aldrich). The residual solvent was removed by distillation at reduced pressure. The residue obtained was purified by elution in a silica gel chromatography column [eluent: mixture of n-heptane (Aldrich)/dichloromethane (Aldrich) in a ratio of 9/1 (v/v)], obtaining 250 mg of 5,6-diphenoxy-4,7-bis[5-(2,5-dimethylphenyl)-2-thienyl]benzo[c]1,2,5-thiadiazole of formula (Ig) [5-(2,5-Me.sub.2Ph).sub.2DTB(OPh).sub.2] (yield=90%).

EXAMPLE 9

Synthesis of 5,6-diphenoxy-4,7-bis[5-(2,6-di-iso-propylonenyl)-2-thienyl]benzo[c]1,2,5-thiadiazole of formula (Ih)

(17) ##STR00027##

(18) In a 100 ml flask, fitted with a magnetic stirrer, thermometer and condenser, in inert atmosphere, 2,6-di-iso-propylphenylboronic acid (Aldrich) (387 mg; 1.8 mmoles) and caesium carbonate (Aldrich) (940 mg; 2.88 mmoles) were added to a solution of 5,6-diphenoxy-4,7-bis(5-bromo-2-thienyl)-2,1,3-benzothiadiazole of formula (a) obtained as described in Example 6 (300 mg; 0.47 mmoles) in 1,4-dioxane (Aldrich) (5 ml). After having removed the air present by means of 3 vacuum/nitrogen cycles, bis-triphenylphosphine palladium dichloride (Aldrich) (34 mg; 0.048 mmoles) was added obtaining a reaction mixture which was heated to 85° C. and held at the said temperature, with stirring, for 14 hours. The reaction mixture was then poured into distilled water (50 ml) and extracted with dichloromethane (Aldrich) (3×25 ml). The organic phase obtained was washed to neutral with distilled water (3×25 ml), and then dried over sodium sulfate (Aldrich). The residual solvent was removed by distillation at reduced pressure. The residue obtained was purified by elution in a silica gel chromatography column [eluent: mixture of n-heptane (Aldrich)/dichloromethane (Aldrich) in a ratio of 9/1 (v/v)], obtaining 270 mg of 5,6-diphenoxy-4,7-bis[5-(2,6-di-iso-propylphenyl)-2-thienyl]benzo[c]1,2,5-thiadiazole of formula (Ih) [5-(2,6-Pr.sup.i.sub.2Ph).sub.2DTB(OPh).sub.2] (yield=71%).

EXAMPLE 10

Synthesis of 5,6-diphenoxy-4,7-bis[5-(2-naphthyl)-2-thienyl]benzo[c]1,2,5-thiadiazole of formula (Ii)

(19) ##STR00028##

(20) In a 100 ml flask, fitted with a magnetic stirrer, thermometer and condenser, in inert atmosphere, 2-naphthylboronic acid (Aldrich) (178 mg; 1.03 mmoles) and an aqueous solution of 2.1 M of potassium carbonate (Aldrich) (419 mg in 1.44 ml of water; 3.04 mmoles) were added to a solution of 5,6-diphenoxy-4,7-bis(5-bromo-2-thienyl)-2,1,3-benzothiadiazole of formula (a) obtained as described in Example 6 (245.8 mg; 0.38 mmoles) in 1,4-dioxane (Aldrich) (15 ml). After having removed the air present by means of 3 vacuum/nitrogen cycles, palladium-tetrakistriphenylphosphine (Aldrich) (22 mg; 0.02 mmoles) (Aldrich) was added, obtaining a reaction mixture which was heated to 95° C. and held at the said temperature, with stirring, for 14 hours. The reaction mixture was then poured into distilled water (50 ml) and extracted with dichloromethane (Aldrich) (3×25 ml). The organic phase obtained was washed to neutral with distilled water (3×25 ml) and then dried over sodium sulfate (Aldrich). The residual solvent was removed by distillation at reduced pressure. The residue obtained was purified by elution in a silica gel chromatography column [eluent: mixture of n-heptane (Aldrich)/ethyl acetate (Aldrich) in a ratio of 85/15 (v/v)], obtaining 250 mg of 5,6-diphenoxy-4,7-bis[5-(2-naphthyl)-2-thienyl]benzo[c]1,2,5-thiadiazole of formula (Ii) [5-(2-Naph).sub.2DTB(OPh).sub.2] (yield=89%).

EXAMPLE 11 (COMPARATIVE)

(21) 6 g of Altuglas VSUVT 100 (PMMA) polymethylmethacrylate and 49.5 mg of 4,7-di-(thien-2′-yl)-2,1,3-benzothiadiazole (DTB), were dissolved in 30 ml of 1,2-dichlorobenzene (Aldrich). The solution obtained was then deposited uniformly on a sheet of polymethylmethacrylate (dimensions 300 mm×90 mm×6 mm) using a “Doctor Blade” type film applicator and the solvent was allowed to evaporate at ambient temperature (25° C.), in a gentle flow of air, for 24 hours. This yielded a transparent sheet of a yellow colour imparted by the film, whose thickness was ranging from 100 μm to 50 μm.

(22) An IXYS-KXOB22-12 photovoltaic cell having a surface area of 1.2 cm.sup.2 was then applied to one of the edges of the polymer sheet

(23) The main surface of the polymer sheet [that coated with the thin film containing the 4,7-di-(thien-2′-yl)-2,1,3-benzothiadiazole (DTB)] was then illuminated with a light source having a power of 1 sun (1000 W/m.sup.2) and the electrical power generated by the illumination was then measured.

(24) Power (P) was then measured by illuminating one portion of sheet of dimensions 100 mm×90 mm at an increasing distance (d) from the edge to which the photovoltaic cell was attached. These measurements at a variable distance from the photovoltaic cell help to quantify the contributions of wave guide, edge and autoabsorption effects.

(25) FIG. 1 shows the graph for the power (P) generated, expressed in mW (shown in the ordinate), as a function of distance (d) from the edge to which the photovoltaic cell was attached, expressed in cm (shown in the abscissa).

(26) It will be seen how in the absence of edge effects the mean power generated was 5.69 mW (FIG. 1).

(27) FIG. 2 shows the obtained value of the power (P) generated, expressed in mW (shown in the ordinate), (the number of the example is shown in the abscissa).

EXAMPLE 12

(28) 6 g of Altuglas VSUVT 100 (PMMA) polymethylmethacrylate and 87.1 mg of 5,6-diphenoxy-4,7-bis(2-thienyl)-2,1,3-benzothiadiazole of formula (Ia) [DTB(OPh).sub.2] obtained as described in Example 1, were dissolved in 30 ml of 1,2-dichlorobenzene (Aldrich). The solution obtained was then deposited uniformly on a sheet of polymethylmethacrylate (dimensions 300 mm×90 mm×6 mm) using a “Doctor Blade” type film applicator and the solvent was allowed to evaporate at ambient temperature (25° C.), in a gentle flow of air, for 24 hours. This yielded a transparent sheet of a red colour imparted by the film, whose thickness was ranging from 100 μm to 50 μm.

(29) An IXYS-KXOB22-12 photovoltaic cell having a surface area of 1.2 cm.sup.2 was then applied to one of the edges of the polymer sheet.

(30) The main surface of the polymer sheet (that coated with the thin film) was then illuminated with a light source having a power of 1 sun (1000 W/m.sup.2) and the electrical power generated by the illumination was then measured.

(31) Power (P) was then measured by illuminating one portion of sheet of dimensions 100 mm×90 mm at an increasing distance (d) from the edge to which the photovoltaic cell was attached. These measurements at a variable distance from the photovoltaic cell help to quantify the contributions of wave guide, edge, diffusion and autoabsorption effects.

(32) FIG. 1 shows the graph for the power (P) generated, expressed in mW (shown in the ordinate), as a function of distance (d) from the edge to which the photovoltaic cell was attached, expressed in cm (shown in the abscissa).

(33) It will be seen how in the absence of edge effects the mean power generated was 8.49 mW (FIG. 1).

(34) FIG. 2 shows the obtained value of the power (P) generated, expressed in mW (shown in the ordinate), (the number of the example is shown in the abscissa).

EXAMPLE 13

(35) 6 g of Altuglas VSUVT 100 (PMMA) polymethylmethacrylate and 105 mg of 5,6-di(4-t-butylphenoxy)-4,7-bis(2-thienyl)-2,1,3-benzothiadiazole of formula (Ib) [DTB(OPh-Bu.sup.t).sub.2] obtained as described in Example 2 were dissolved in 30 ml of 1,2-dichlorobenzene (Aldrich). The solution obtained was then deposited uniformly on a sheet of polymethylmethacrylate (dimensions 300 mm×90 mm×6 mm) using a “Doctor Blade” type film applicator and the solvent was allowed to evaporate at ambient temperature (25° C.), in a gentle flow of air, for 24 hours. This yielded a transparent sheet of an orange colour imparted by the film, whose thickness was ranging from 100 μm to 50 μm.

(36) An IXYS-KXOB22-12 photovoltaic cell having a surface area of 1.2 cm.sup.2 was then applied to one of the edges of the polymer sheet.

(37) The main surface of the polymer sheet (that coated with the thin film) was then illuminated with a light source having a power of 1 sun (1000 W/m.sup.2) and the electrical power generated by the illumination was then measured.

(38) Power (P) was then measured by illuminating one portion of sheet of dimensions 100 mm×90 mm at an increasing distance (d) from the edge to which the photovoltaic cell was attached. These measurements at a variable distance from the photovoltaic cell help to quantify the contributions of wave guide, edge, diffusion and autoabsorption effects.

(39) FIG. 1 shows the graph for the power (P) generated, expressed in mW (shown in the ordinate), as a function of distance (d) from the edge to which the photovoltaic cell was attached, expressed in cm (shown in the abscissa).

(40) It will be seen how in the absence of edge effects the mean power generated was 5.98 mW (FIG. 1).

(41) FIG. 2 shows the obtained value of the power (P) generated, expressed in mW (shown in the ordinate), (the number of the example is shown in the abscissa).

EXAMPLE 14

(42) 6 g of Altuglas VSUVT 100 (PMMA) polymethylmethacrylate and 105.2 mg of 5,6-di(2-naphthoxy)-4,7-bis(2-thienyl)-2,1,3-benzothiadiazole of formula (Ic) [DTB(O-2-Naph).sub.2] obtained as described in Example 3, were dissolved in 30 ml of 1,2-dichlorobenzene (Aldrich). The solution obtained was then deposited uniformly on a sheet of polymethylmethacrylate (dimensions 300 mm×90 mm×6 mm) using a “Doctor Blade” type film applicator and the solvent was allowed to evaporate at ambient temperature (25° C.), in a gentle flow of air, for 24 hours. This yielded a transparent sheet of an orange colour imparted by the film, whose thickness was ranging from 100 μm to 50 μm.

(43) An IXYS-KXOB22-12 photovoltaic cell having a surface area of 1.2 cm.sup.2 was then applied to one of the edges of the polymer sheet.

(44) The main surface of the polymer sheet (that coated with the thin film) was then illuminated with a light source having a power of 1 sun (1000 W/m.sup.2) and the electrical power generated by the illumination was then measured.

(45) Power (P) was then measured by illuminating one portion of sheet of dimensions 100 mm×90 mm at an increasing distance (d) from the edge to which the photovoltaic cell was attached. These measurements at a variable distance from the photovoltaic cell help to quantify the contributions of wave guide, edge, diffusion and autoabsorption effects.

(46) FIG. 1 shows the graph for the power (P) generated, expressed in mW (shown in the ordinate), as a function of distance (d) from the edge to which the photovoltaic cell was attached, expressed in cm (shown in the abscissa).

(47) It will be seen how in the absence of edge effects the mean power generated was 7.48 mW (FIG. 1).

(48) FIG. 2 shows the obtained value of the power (P) generated, expressed in mW (shown in the ordinate), (the number of the example is shown in the abscissa).

EXAMPLE 15

(49) 6 g of Altuglas VSUVT 100 (PMMA) polymethylmethacrylate and 82.6 mg of 5,6-di(4-phenylphenoxy)-4,7-bis(2-thienyl)-2,1,3-benzothiadiazole of formula (Id) [DTB(OBPh).sub.2] obtained as described in Example 4, were dissolved in 30 ml of 1,2-dichlorobenzene (Aldrich). The solution obtained was then deposited uniformly on a sheet of polymethylmethacrylate (dimensions 300 mm×90 mm×6 mm) using a “Doctor Blade” type film applicator and the solvent was allowed to evaporate at ambient temperature (25° C.), in a gentle flow of air, for 24 hours. This yielded a transparent sheet of an orange colour imparted by the film, whose thickness was ranging from 100 μm to 50 μm.

(50) An IXYS-KXOB22-12 photovoltaic cell having a surface area of 1.2 cm.sup.2 was then applied to one of the edges of the polymer sheet.

(51) The main surface of the polymer sheet (that coated with the thin film) was then illuminated with a light source having a power of 1 sun (1000 W/m.sup.2) and the electrical power generated by the illumination was then measured.

(52) Power (P) was then measured by illuminating one portion of sheet of dimensions 100 mm×90 mm at an increasing distance (d) from the edge to which the photovoltaic cell was attached. These measurements at a variable distance from the photovoltaic cell help to quantify the contributions of wave guide, edge, diffusion and autoabsorption effects.

(53) FIG. 1 shows the graph for the power (P) generated, expressed in mW (shown in the ordinate), as a function of distance (d) from the edge to which the photovoltaic cell was attached, expressed in cm (shown in the abscissa).

(54) It will be seen how in the absence of edge effects the mean power generated was 7.06 mW (FIG. 1).

(55) FIG. 2 shows the obtained value of the power (P) generated, expressed in mW (shown in the ordinate), (the number of the example is shown in the abscissa).

EXAMPLE 16

(56) 6 g of Altuglas VSUVT 100 (PMMA) polymethylmethacrylate and 97.2 mg of 5,6-di(2,6-dimethylphenoxy)-4,7-bis(2-thienyl)-2,1,3-benzothiadiazole of formula (Ie) [DTB(OPh-2,6-Me.sub.2).sub.2] obtained as described in Example 5, were dissolved in 30 ml of 1,2-dichlorobenzene (Aldrich). The solution obtained was then deposited uniformly on a sheet of polymethylmethacrylate (dimensions 300 mm×90 mm×6 mm) using a “Doctor Blade” type film applicator and the solvent was allowed to evaporate at ambient temperature (25° C.), in a gentle flow of air, for 24 hours. This yielded a transparent sheet of an orange colour imparted by the film, whose thickness was ranging from 100 μm to 50 μm.

(57) An IXYS-KXOB22-12 photovoltaic cell having a surface area of 1.2 cm.sup.2 was then applied to one of the edges of the polymer sheet.

(58) The main surface of the polymer sheet (that coated with the thin film) was then illuminated with a light source having a power of 1 sun (1000 W/m.sup.2) and the electrical power generated by the illumination was then measured.

(59) Power (P) was then measured by illuminating one portion of sheet of dimensions 100 mm×90 mm at an increasing distance (d) from the edge to which the photovoltaic cell was attached. These measurements at a variable distance from the photovoltaic cell help to quantify the contributions of wave guide, edge, diffusion and autoabsorption effects.

(60) FIG. 1 shows the graph for the power (P) generated, expressed in mW (shown in the ordinate), as a function of distance (d) from the edge to which the photovoltaic cell was attached, expressed in cm (shown in the abscissa).

(61) It will be seen how in the absence of edge effects the mean power generated was 6.73 mW (FIG. 1).

(62) FIG. 2 shows the obtained value of the power (P) generated, expressed in mW (shown in the ordinate), (the number of the example is shown in the abscissa).

EXAMPLE 17

(63) 6 g of Altuglas VSUVT 100 (PMMA) polymethylmethacrylate and 124.6 mg of 5,6-diphenoxy-4,7-bis[5-(2,6-dimethylphenyl)-2-thienyl]benzo[c]1,2,5-thiadiazole of formula (If) [5-(2,6-Me.sub.2Ph).sub.2DTB(OPh).sub.2] obtained as described in Example 7, were dissolved in 30 ml of 1,2-dichlorobenzene (Aldrich). The solution obtained was then deposited uniformly on a sheet of polymethylmethacrylate (dimensions 300 mm×90 mm×6 mm) using a “Doctor Blade” type film applicator and the solvent was allowed to evaporate at ambient temperature (25° C.), in a gentle flow of air, for 24 hours. This yielded a transparent sheet of an orange colour imparted by the film, whose thickness was ranging from 100 μm to 50 μm.

(64) An IXYS-KXOB22-12 photovoltaic cell having a surface area of 1.2 cm.sup.2 was then applied to one of the edges of the polymer sheet.

(65) The main surface of the polymer sheet (that coated with the thin film) was then illuminated with a light source having a power of 1 sun (1000 W/m.sup.2) and the electrical power generated by the illumination was then measured.

(66) Power (P) was then measured by illuminating one portion of sheet of dimensions 100 mm×90 mm at an increasing distance (d) from the edge to which the photovoltaic cell was attached. These measurements at a variable distance from the photovoltaic cell help to quantify the contributions of wave guide, edge, diffusion and autoabsorption effects.

(67) FIG. 1 shows the graph for the power (P) generated, expressed in mW (shown in the ordinate), as a function of distance (d) from the edge to which the photovoltaic cell was attached, expressed in cm (shown in the abscissa).

(68) It will be seen how in the absence of edge effects the mean power generated was 10.58 mW (FIG. 1).

(69) FIG. 2 shows the obtained value of the power (P) generated, expressed in mW (shown in the ordinate), (the number of the example is shown in the abscissa).

EXAMPLE 18

(70) 6 g of Altuglas VSUVT 100 (PMMA) polymethylmethacrylate and 124.6 mg of 5,6-diphenoxy-4,7-bis[5-(2,5-dimethylphenyl)-2-thienyl]benzo[c]1,2,5-thiadiazole of formula (Ig) [5-(2,5-Me.sub.2Ph).sub.2DTB(OPh).sub.2] obtained as described in Example 8, were dissolved in 30 ml of 1,2-dichlorobenzene (Aldrich). The solution obtained was then deposited uniformly on a sheet of polymethylmethacrylate (dimensions 300 mm×90 mm×6 mm) using a “Doctor Blade” type film applicator and the solvent was allowed to evaporate at ambient temperature (25° C.), in a gentle flow of air, for 24 hours. This yielded a transparent sheet of an orange colour imparted by the film, whose thickness was ranging from 100 μm to 50 μm.

(71) An IXYS-KXOB22-12 photovoltaic cell having a surface area of 1.2 cm.sup.2 was then applied to one of the edges of the polymer sheet.

(72) The main surface of the polymer sheet (that coated with the thin film) was then illuminated with a light source having a power of 1 sun (1000 W/m.sup.2) and the electrical power generated by the illumination was then measured.

(73) Power (P) was then measured by illuminating one portion of sheet of dimensions 100 mm×90 mm at an increasing distance (d) from the edge to which the photovoltaic cell was attached. These measurements at a variable distance from the photovoltaic cell help to quantify the contributions of wave guide, edge, diffusion and autoabsorption effects.

(74) FIG. 1 shows the graph for the power (P) generated, expressed in mW (shown in the ordinate), as a function of distance (d) from the edge to which the photovoltaic cell was attached, expressed in cm (shown in the abscissa).

(75) It will be seen how in the absence of edge effects the mean power generated was 13.17 mW (FIG. 1).

(76) FIG. 2 shows the obtained value of the power (P) generated, expressed in mW (shown in the ordinate), (the number of the example is shown in the abscissa).

EXAMPLE 19

(77) 6 g of Altuglas VSUVT 100 (PMMA) polymethylmethacrylate and 144.7 mg of 5,6-diphenoxy-4,7-bis[5-(2,6-di-iso-propylphenyl)-2-thienyl]benzo[c]1,2,5-thiadiazole of formula (Ih) [5-(2,6-Pr.sup.i.sub.2Ph).sub.2DTB(OPh).sub.2] obtained as described in Example 9, were dissolved in 30 ml of 1,2-dichlorobenzene (Aldrich). The solution obtained was then deposited uniformly on a sheet of polymethylmethacrylate (dimensions 300 mm×90 mm×6 mm) using a “Doctor Blade” type film applicator and the solvent was allowed to evaporate at ambient temperature (25° C.), in a gentle flow of air, for 24 hours. This yielded a transparent sheet of an orange colour imparted by the film, whose thickness was ranging from 100 μm to 50 μm.

(78) An IXYS-KXOB22-12 photovoltaic cell having a surface area of 1.2 cm.sup.2 was then applied to one of the edges of the polymer sheet.

(79) The main surface of the polymer sheet (that coated with the thin film) was then illuminated with a light source having a power of 1 sun (1000 W/m.sup.2) and the electrical power generated by the illumination was then measured.

(80) Power (P) was then measured by illuminating one portion of sheet of dimensions 100 mm×90 mm at an increasing distance (d) from the edge to which the photovoltaic cell was attached. These measurements at a variable distance from the photovoltaic cell help to quantify the contributions of wave guide, edge, diffusion and autoabsorption effects.

(81) FIG. 1 shows the graph for the power (P) generated, expressed in mW (shown in the ordinate), as a function of distance (d) from the edge to which the photovoltaic cell was attached, expressed in cm (shown in the abscissa).

(82) It will be seen how in the absence of edge effects the mean power generated was 5.28 mW (FIG. 1).

(83) FIG. 2 shows the value of the power (P) generated, expressed in mW (shown in the ordinate), (the number of the example is shown in the abscissa).

EXAMPLE 20

(84) 6 g of Altuglas VSUVT 100 (PMMA) polymethylmethacrylate and 49.5 mg of 5,6-diphenoxy-4,7-bis[5-(2-naphthyl)-2-thienyl]benzo[c]1,2,5-thiadiazole of formula (Ii) [5-(2-Naph).sub.2DTB(OPh).sub.2] obtained as described in Example 10, were dissolved in 30 ml of 1,2-dichlorobenzene (Aldrich). The solution obtained was then deposited uniformly on a sheet of polymethylmethacrylate (dimensions 300 mm×90 mm×6 mm) using a “Doctor Blade” type film applicator and the solvent was allowed to evaporate at ambient temperature (25° C.), in a gentle flow of air, for 24 hours. This yielded a transparent sheet of an orange colour imparted by the film, whose thickness was ranging from 100 μm to 50 μm.

(85) An IXYS-KXOB22-12 photovoltaic cell having a surface area of 1.2 cm.sup.2 was then applied to one of the edges of the polymer sheet.

(86) The main surface of the polymer sheet (that coated with the thin film) was then illuminated with a light source having a power of 1 sun (1000 W/m.sup.2) and the electrical power generated by the illumination was then measured.

(87) Power (P) was then measured by illuminating one portion of sheet of dimensions 100 mm×90 mm at an increasing distance (d) from the edge to which the photovoltaic cell was attached. These measurements at a variable distance from the photovoltaic cell help to quantify the contributions of wave guide, edge, diffusion and autoabsorption effects.

(88) FIG. 1 shows the graph for the power (P) generated, expressed in mW (shown in the ordinate), as a function of distance (d) from the edge to which the photovoltaic cell was attached, expressed in cm (shown in the abscissa).

(89) It will be seen how in the absence of edge effects the mean power generated was 9.09 mW (FIG. 1).

(90) FIG. 2 shows the obtained value of the power (P) generated, expressed in mW (shown in the ordinate), (the number of the example is shown in the abscissa).

EXAMPLE 21 (COMPARATIVE) 22-24 (INVENTION)

(91) 400 ml of methyl methacrylate (MMA) (Aldrich 99%), previously distilled, were heated to 80° C., in 2 hours, under magnetic agitation, in a 1 liter flask. Subsequently, 40 mg of azo-bis-iso-butyronitrile (AIBN) (Aldrich 98%) dissolved in 40 ml of methyl methacrylate (MMA) (Aldrich 99%), previously distilled, were added: the mixture obtained was heated, under magnetic agitation, to 94° C., in 1 hour, left at said temperature for 2 minutes, and subsequently cooled in an ice bath, obtaining a syrup of pre-polymerized polymethyl-methacrylate (PMMA).

(92) 400 ml of the pre-polymerized syrup obtained as described above were loaded into a 1 liter flask, and 25 mg of lauroyl peroxide (Acros 99%) dissolved in methyl methacrylate (MMA) (Aldrich 99%), previously distilled, were added, and a quantity of 4,7-di(thien-2′-il)-2,1,3-benzothiadiazole (DTB) [in Example 21 (comparative)] or of disubstituted diaryloxybenzoheterodiazole compound of general formula (I), obtained as described in the examples reported above [in Examples 22 (invention): compound (Ia) of Example 1; in Example 23 (invention): compound (If) of Example 7; and in Example 24 (invention): compound (Ig) of Example 8], such that the molar percentage of said 4,7-di(thien-2′-il)-2,1,3-benzothiadiazole (DTB) or of said disubstituted diaryloxybenzoheterodiazole compound of general formula (I), with respect to methyl methacrylate (MMA) is equal to 0.3. The mixture obtained was degassed, under magnetic agitation, under a vacuum of 10 mm mercury (Hg), for 45 minutes, at ambient temperature (25° C.), obtaining a solution that was poured into the mold described below.

(93) Said mold was formed by two sheets of glass with dimensions 40×40 cm and thickness 6 mm-10 mm, separated by polyvinylchloride (PVC) gaskets (10 cm diameter). Said sheets of glass were mounted between jaws and pressed together until the space between the two sheets was about 6 mm. After closing the opening through which the aforementioned solution was poured with the gasket, the mold was immersed in a water bath, at 55° C., for 48 hours, and then placed in the stove and heated to 95° C. for 24 hours. Subsequently, the mold was cooled to ambient temperature (25° C.), the jaws and the gasket were removed, the glass sheets of the mold were separated, and the sheet of polymethylmethacrylate (PMMA) obtained was collected. The sheet of polymethyl-methacrylate (PMMA) was then cut into sheets with dimensions 30×7.5 cm in order to carry out the aging tests reported below.

(94) The different sheets obtained as described above were subjected to accelerated aging in an ATLAS XenoTest Beta+, equipped with a Xenon lamp cooled in air and with Xenochrome 300 filter, operating in accordance with standard DIN EN ISO 4892-2-Al 2003-11.

(95) Periodically, the sheets were removed and subjected to UV-visible spectroscopy.

(96) The ultraviolet and visible absorption spectra (190 nm-850 nm) were recorded with a double beam UV-Vis-NIR spectrophotometer and double monochromator, with a passband of 2.0 nm and step of 1 nm.

(97) Therefore, through said UV-visible spectroscopy, the quantity of fluorescent compound present on the sheets was determined by measuring the characteristic absorbance of each fluorescent compound, subject to calibration through reference sheets containing known quantities of fluorescent compound dispersed in the polymeric matrix itself.

(98) In the sheets subject to accelerated aging the spectrophotometry of UV-vis absorption allowed the absorbance reduction in the visible region to be monitored by measuring the relative absorbance percentage (A %) defined as (At)/(A0), i.e. the ratio of absorbance at time t (At) to absorbance at time 0 (A0): in particular, the absorbance values (At) and (A0) are the mean of the absorbance values measured on each sheet in various points, at time t and at time zero, respectively.

(99) Table 2 reports the relative absorbance percentage values (A %) [(At)/(A0)] according to the aging time [t (h)].

(100) TABLE-US-00002 TABLE 2 (A %) [(At)/(A0)] Example 24 Example 21 Example 22 Example 23 [compound t (h) (DTB) [compound (Ia)] [compound (If)] (Ig)] 0 100 100 100 100 300 84 93 98 96 500 66 87 100 95 900 — 79 96 91 1000 51 — — — 1500 32 64 93 85 1800 17 — 92 82 2000 — — — —

(101) From the data reported in Table 2 it can be inferred that the fluorescent compounds in accordance with the present invention (Examples 22-24) have a higher relative absorbance percentage (A %) even after a number of hours of aging, with respect to 4,7-di(thien-2′-yl)-2,1,3-benzothiadiazole (DTB) known in the art [Example 21 (comparative)].