CONJUGATED ANTHRADITHIOPHENE TERPOLYMERS AND PHOTOVOLTAIC DEVICES CONTAINING THEM

Abstract

A conjugated anthradithiophene terpolymer having general formula (I):

##STR00001##

wherein Q, equal or different from each other, represent a nitrogen atom; W, equal or different from each other, represent a hydrogen atom; W.sub.1, equal or different from each other, represent a hydrogen atom; X, equal or different from each other, represent a sulfur atom, an oxygen atom, a selenium atom; Y, equal or different from each other, represent an oxygen atom, a sulfur atom; Z, equal or different from each other, are selected from amino groups NR.sub.2R.sub.3 wherein R.sub.2represents a hydrogen atom; A represents an electron-acceptor group; an electron-donor group; l and m, equal or different from each other, represent an integer ranging from 1 to 9; and n is an integer ranging from 10 to 500.

Claims

1. A conjugated anthradithiophene terpolymer having general formula (I): ##STR00031## wherein Q, equal or different from each other, represent a nitrogen atom; or they are selected from CR.sub.1 groups wherein R.sub.1 represents a hydrogen atom, or is selected from C.sub.1-C.sub.20 alkyl groups, preferably C.sub.2-C.sub.10, linear or branched, optionally substituted cycloalkyl groups, optionally substituted aryl groups, optionally substituted heteroaryl groups; W, equal or different from each other, represent a hydrogen atom; or they are selected from C.sub.1-C.sub.20 alkyl groups, preferably C.sub.2-C.sub.10, linear or branched; W.sub.1, equal or different from each other, represent a hydrogen atom; or they are selected from C.sub.1-C.sub.20 alkyl groups, preferably C.sub.2-C.sub.10, linear or branched; X, equal or different from each other, represent a sulfur atom, an oxygen atom, a selenium atom; Y, equal or different from each other, represent an oxygen atom, a sulfur atom; Z, equal or different from each other, are selected from amino groups NR.sub.2R.sub.3 wherein R.sub.2 represents a hydrogen atom, or is selected from C.sub.1-C.sub.20, preferably C.sub.2-C.sub.10, linear or branched alkyl groups, or is selected from optionally substituted cycloalkyl groups and R.sub.3 is selected from C.sub.1-C.sub.20 alkyl groups, preferably C.sub.2-C.sub.10, linear or branched, or is selected from optionally substituted cycloalkyl groups; or they are selected from OR.sub.4 groups wherein R.sub.4 is selected from C.sub.1-C.sub.30 alkyl groups, preferably C.sub.2-C.sub.24, linear or branched, optionally substituted cycloalkyl groups, optionally substituted aryl groups, optionally substituted heteroaryl groups; or they are selected from R.sub.5O[CH.sub.2CH.sub.2O].sub.n1-polyethyleneoxy groups wherein R.sub.5 is selected from C.sub.1-C.sub.20 alkyl groups, preferably C.sub.2-C.sub.10, linear or branched, and n1 is an integer ranging from 1 to 4; or they are selected from R.sub.6OR.sub.7 groups wherein R.sub.6 is selected from C.sub.1-C.sub.20 alkylene groups, preferably C.sub.2-C.sub.10, linear or branched and R.sub.7 represents a hydrogen atom or is selected from C.sub.1-C.sub.20 alkyl groups, preferably C.sub.2-C.sub.10, linear or branched; or they are selected from R.sub.5[OCH.sub.2CH.sub.2].sub.n1-polyethyleneoxy groups wherein R.sub.5 has the same meanings reported above and n1 is an integer ranging from 1 to 4; or they are selected from RS-thiol groups wherein R is selected from C.sub.1-C.sub.20, preferably C.sub.2-C.sub.10, linear or branched alkyl groups; A represents an electron-acceptor group; an electron-donor group; or is selected from optionally substituted aryl groups, optionally substituted heteroaryl groups; l and m, equal or different from each other, represent an integer ranging from 1 to 9; and n is an integer ranging from 10 to 500.

2. The conjugated anthradithiophenic terpolymer having general formula (I) according to claim 1, wherein said group A is selected from the groups reported in Table 1: TABLE-US-00003 TABLE 1 wherein: B represents a sulfur atom, an oxygen atom, a selenium atom, or is selected from NR.sub.11 groups wherein R.sub.11 represents a hydrogen atom, or is selected from C.sub.1-C.sub.20 alkyl groups, preferably C.sub.2-C.sub.10, linear or branched, optionally substituted cycloalkyl groups, optionally substituted aryl groups, optionally substituted heteroaryl groups; Q.sub.1 and Q.sub.2, equal or different from each other, represent a nitrogen atom, a sulfur atom, an oxygen atom, a selenium atom; or they are selected from CR.sub.12 groups wherein R.sub.12 represents a hydrogen atom, or is selected from C.sub.1-C.sub.20 alkyl groups, preferably C.sub.2-C.sub.10, linear or branched, optionally substituted cycloalkyl groups, optionally substituted aryl groups, optionally substituted heteroaryl groups; R.sub.8, equal or different from each other, are selected from C.sub.1-C.sub.20 alkyl groups, preferably C.sub.2-C.sub.10, linear or branched, optionally halogenated, optionally substituted cycloalkyl groups, optionally substituted aryl groups, optionally substituted heteroaryl groups, C.sub.1-C.sub.20 alkoxyl groups, preferably C.sub.2-C.sub.10, linear or branched; or they are selected from polyethyleneoxy groups R.sub.13[OCH.sub.2CH.sub.2].sub.n wherein R.sub.13 is selected from C.sub.1-C.sub.20 alkyl groups, preferably C.sub.2-C.sub.10, linear or branched, and n is an integer ranging from 1 to 4; or they are selected from R.sub.14OR.sub.14 groups wherein R.sub.14 represents a hydrogen atom, or is selected from C.sub.1-C.sub.20 alkyl groups, preferably C.sub.2-C.sub.10, linear or branched, optionally substituted cycloalkyl groups, optionally substituted aryl groups, optionally substituted heteroaryl groups; or they are selected from COOR.sub.15 groups wherein R.sub.15 represents a hydrogen atom, or is selected from C.sub.1-C.sub.20 alkyl groups, preferably C.sub.2-C.sub.10, linear or branched, optionally substituted cycloalkyl groups, optionally substituted aryl groups, optionally substituted heteroaryl groups; or represent a CHO group, or a cyano group (CN); and R.sub.9 and R.sub.10, equal or different from each other, represent a hydrogen atom, a fluorine atom, a chlorine atom; or they are selected from C.sub.1-C.sub.20 alkyl groups, preferably C.sub.2-C.sub.10, linear or branched, optionally substituted cycloalkyl groups, optionally substituted aryl groups, C.sub.1-C.sub.20 alkoxyl groups, preferably C.sub.2-C.sub.10, linear or branched; or they are selected from polyethyleneoxy groups R.sub.13[OCH.sub.2CH.sub.2].sub.n in which R.sub.13 has the same meanings reported above and n is an integer ranging from 1 to 4; or they are selected from R.sub.14OR.sub.14 groups wherein R.sub.14 has the same meanings reported above; or they are selected from COR.sub.15 groups in which R.sub.15 has the same meanings reported above; or they are selected from COOR.sub.15 groups in which R.sub.15 has the same meanings reported above; or they represent a CHO group, or a cyano group (CN); or, R.sub.9 and R.sub.10, can optionally be bonded together so as to form, together with the carbon atoms to which they are bonded, a cycle or a polycyclic system containing from 3 to 14 carbon atoms, preferably from 4 to 6 carbon atoms, saturated, unsaturated, or aromatic, optionally containing one or more heteroatoms such as oxygen, sulfur, nitrogen, silicon, phosphorus, selenium.

3. The conjugated anthradithiophene terpolymer having general formula (I) according to claim 1, wherein Q represents a CR.sub.1 group wherein R.sub.1 represents a hydrogen atom; W, equal to each other, represent a hydrogen atom; W.sub.1, equal to each other, represent a C.sub.1-C.sub.20 alkyl group, linear or branched, preferably are a 2-ethylhexyl group; X, equal to each other, represent a sulfur atom; Y, equal to each other, represent an oxygen atom; Z, equal to each other, represent a OR.sub.4 group wherein R.sub.4 represents a linear or branched C.sub.1-C.sub.30 alkyl group, preferably are a 2-octyldodecyloxy group; and A represents an electron-acceptor group or an electron-donor group wherein B represents a sulfur atom, Q.sub.1 and Q.sub.2, equal to each other, represent a CR.sub.12 group wherein R.sub.12 is selected from C.sub.1-C.sub.20 alkyl groups, preferably is an octyl, R.sub.9 and R.sub.10, equal to each other, represent a fluorine atom; or represents an electron-acceptor group or an electron-donor group wherein B represents a sulfur atom and R.sub.8 is selected from linear or branched C.sub.1-C.sub.20 alkyl groups, optionally halogenated, preferably is trifluoroethyl.

4. A photovoltaic device (or solar device) such as a photovoltaic cell (or solar cell), a photovoltaic module (or solar module), either on a rigid support or on a flexible support, comprising at least one conjugated anthradithiophenic terpolymer having general formula according to claim 1.

Description

DETAILED DESCRIPTION

[0094] In order to better understand the present disclosure and to put it into practice, some illustrative and non-limiting examples thereof are reported below.

EXAMPLES

Characterisation of the Terpolymers Obtained

Determination of the Molecular Weight

[0095] The molecular weight of the terpolymers obtained by operating in accordance with the following examples, was determined by Gel Permeation Chromatography (GPC) on a WATERS 150 C instrument, using HT5432 columns, with trichlorobenzene eluent, at 80? C.

[0096] The weight average molecular weight (M.sub.w), the number average molecular weight (M.sub.n) and the polydispersity index (PDI), corresponding to the M.sub.w/M.sub.n ratio, are given.

Determination of the Optical Band-Gap

[0097] The terpolymers obtained by operating in accordance with the following examples, were characterized by UV-Vis-NIR spectroscopy to determine the energetic entity of the optical band-gap in solution or on thin film according to the following procedure.

[0098] In the case that the optical band-gap was measured in solution, the terpolymer was dissolved in toluene, chloroform, chlorobenzene, dichlorobenzene, trichlorobenzene, or other suitable solvent. The solution thus obtained was placed in a quartz cuvette and analysed in transmission by means of a double-beam UV-Vis-NIR spectrophotometer and double monochromator Perkin Elmer ?950, in the range 200 nm-850 nm, with a 2.0 nm bandwidth, scanning speed of 220 nm/min and 1 nm step, using as a reference an identical quartz cuvette containing only the solvent used as a reference.

[0099] In the case that the optical band-gap was measured on thin film, the terpolymer was dissolved in toluene, chloroform, chlorobenzene, dichlorobenzene, trichlorobenzene, or other suitable solvent, obtaining a solution having a concentration equal to about 10 mg/ml, which was deposited by spin-coating on a Suprasil quartz slide. The thin film thus obtained was analysed in transmission by means of a dual-beam UV-Vis-NIR spectrophotometer and double monochromator Perkin Elmer ?950, in the range 200 nm-850 nm, with a 2.0 nm bandwidth, scanning speed of 220 nm/min and 1 nm step, using an identical Suprasil quartz slide as such, as a reference.

[0100] The optical band-gap was estimated from the spectra in transmission by measuring the absorption edge corresponding to the transition from the valence band (VB) to the conduction band (CB). The intersection with the abscissa axis of the straight line tangent to the absorption band at the inflection point was used for the determination of the edge.

[0101] The inflection point (?.sub.F, y.sub.F) was determined on the basis of the coordinates of the minimum of the spectrum in the first derivative, indicated with ?.sub.min and y.sub.min.

The equation of the straight line tangent to the UV-Vis spectrum at the inflection point (?.sub.F, y.sub.F) is as follows:

y=y.sub.min?+y.sub.F?y.sub.min?.sub.min

[0102] Finally, from the condition of intersection with the abscissa axis ?=0, it was obtained:

?.sub.EDGE=(y.sub.min?.sub.min?y.sub.F)/y.sub.min

[0103] Therefore, by measuring the coordinates of the minimum of the first derivative spectrum and the corresponding absorbance value y.sub.F from the UV-Vis spectrum, ?.sub.EDGE was obtained directly by substitution.

[0104] The corresponding energy is:

E.sub.EDGE=h?.sub.EDGE=hc/?.sub.EDGE

wherein: [0105] h=6.626 10?34 Js; [0106] c=2.998 108 ms.sup.?1;
that is:

E.sub.EDGE=1.98810?16J/?.sub.EDGE(nm).

[0107] Lastly, remembering that 1 J=6.24 1018 eV, we have:

E.sub.EDGE=1240eV/?.sub.EDGE(nm).

Determination of HOMO and LUMO

[0108] The determination of the HOMO and LUMO values of the terpolymers obtained by operating in accordance with the following examples, was carried out using the cyclic voltammetry (CV) technique. This technique makes it possible to measure the values of the potentials of formation of the radical cation and radical anion of the sample under examination. These values, inserted in a special equation, allow the HOMO and LUMO values of the terpolymer in question to be obtained. The difference between HOMO and LUMO makes the value of the electrochemical band-gap.

[0109] The values of the electrochemical band-gap are generally higher than the values of the optical band-gap since during the execution of the cyclic voltammetry (CV), the neutral compound is charged and undergoes a conformational reorganization, with an increase in the energy gap, while optical measurement does not lead to the formation of charged species.

[0110] The cyclic voltammetry (CV) measurements were performed with an Autolab PGSTAT12 potentiostat (with GPES Ecochemie software) in a three-electrode cell. In the measurements carried out, an Ag/AgCl electrode was used as the reference electrode, a platinum wire as the counter electrode and a glassy graphite electrode as the working electrode. The sample to be analysed was dissolved in a suitable solvent and subsequently deposited, with a calibrated capillary, on the working electrode, so as to form a film. The electrodes were immersed in a 0.1 M electrolytic solution of 95% tetrabutylammonium tetrafluroborate in acetonitrile. The sample was subsequently subjected to a cyclic potential in the shape of a triangular wave. At the same time, as a function of the applied potential difference, the current, which signals the occurrence of oxidation or reduction reactions of the present species, was monitored.

[0111] The oxidation process corresponds to the removal of an electron from HOMO, while the reduction cycle corresponds to the introduction of an electron into LUMO. The potentials of formation of radical cation and radical anion were derived from the value of the peak onset (E.sub.onset), which is caused by molecules and/or chain segments with HOMO-LUMO levels closer to the edges of the bands. The electrochemical potentials to those related to the electronic levels can be correlated if both refer to the vacuum. For this purpose, the potential of ferrocene in vacuum, known in the literature and equal to ?4.8 eV, was taken as a reference. The inter-solvent redox pair ferrocene/ferrocinium (Fc/Fc.sup.+) was selected because it has an oxide-reduction potential independent of the working solvent.

[0112] The general formula for calculating the energies of the HOMO-LUMO levels is therefore given by the following equation:

E(eV)=?4,8+[E.sub.1/2Ag/AgCl(Fc/Fc.sup.+)?E.sub.onsetAg/AgCl(terpolymer)]

wherein: [0113] E=HOMO or LUMO according to the entered E.sub.onset value; [0114] E.sub.1/2Ag/AgCl=half-wave potential of the peak corresponding to the redox pair ferrocene/ferrocinium measured under the same analysis conditions as the sample and with the same triad of electrodes used for the sample; [0115] E.sub.onsetAg/AgCl=onset potential measured for the terpolymer in the anodic area when calculating HOMO and in the cathodic area when calculating LUMO.

Example 1

Preparation of 2,5-dibromothiophene-3-carboxylic Acid Having Formula (V)

[0116] ##STR00024##

[0117] In a 100 ml flask, fitted with magnetic stirrer, thermometer and refrigerant, in an inert atmosphere, to a solution of 3-thiophenecarboxylic acid (Merck) (4 g; 31 mmol) in N,N-dimethylformamide (DMF) (Merck) (40 ml), at 60? C., it was added N-bromosuccinimide (Merck) (11.57 g; 65 mmol), in small portions, over 15 minutes: the resulting reaction mixture was left, in an inert atmosphere, under stirring, at 60? C., for 24 hours. Subsequently, the reaction mixture was placed in deionised water and ice and the white precipitate obtained was recovered by filtration obtaining a solid. The solid product obtained was dried in a vacuum oven, at 55? C., for 4 hours, obtaining 7.53 g of 2,5-dibromothiophene-3-carboxylic acid having formula (V) (yield 85%).

Example 2

Preparation of 2,2,2-trifluoroethyl-2,5-dibromothiophene-3-carboxylate Having Formula (VI)

[0118] ##STR00025##

[0119] In a 100 ml flask, fitted with magnetic stirrer, thermometer and refrigerant, in an inert atmosphere, to a solution of 2,5-dibromothiophene-3-carboxylic acid having formula (V) obtained as described in Example 1 (1.43 g; 5 mmol) in dichloromethane (DCM) (Merck) (50 ml), at room temperature (25? C.), it was added, N,N-dicyclohexylcarbodiimide (DCC) (Merck) (1.032 g; 5 mmol), 4-(N,N-dimethylamino)pyridine (DMAP) (Merck) (0.357 g; 1.25 mmol) and 2,2,2-trifluoroethanol (Merck) (0.502 g; 5 mmol): the resulting reaction mixture was left, in an inert atmosphere, under stirring, at room temperature (25? C.), for 24 hours. Subsequently, the reaction mixture was placed in a 500 ml separating funnel: deionised water (3?100 ml) was added to said reaction mixture and the whole was extracted with dichloromethane (Merck) (3?100 ml) obtaining an aqueous phase and an organic phase. The entire organic phase (obtained by combining the organic phases deriving from the three extractions) was separated and subsequently dried over anhydrous sodium sulphate (Merck) and evaporated. The residue obtained was purified by elution on a chromatographic column of silica gel [(eluent: n-heptane/dichloromethane 9/1) (Merck)], obtaining 1.656 g of 2,2,2-trifluoroethyl-2,5-dibromothiophene-3-carboxylate having formula (VI) as a white solid (90% yield).

Example 3

Preparation of 2,5-dibromobenzene-1,4-dicarbaldehyde Having Formula (VII)

[0120] ##STR00026##

[0121] In a 100 ml flask, fitted with magnetic stirring, thermometer and coolant, in an inert atmosphere, to a solution of terephthaldehyde (Aldrich) (4.02 g; 30 mmoles) in sulfuric acid (Aldrich) (40 ml) it was added N-bromosuccinaldehyde (Aldrich) (11.57 g; 65 mmoles) in small portions, over 15 minutes: the reaction mixture obtained was left, in an inert atmosphere, under stirring, at room temperature (25? C.), for 3 hours. Subsequently, the reaction mixture was placed in water and ice and the white precipitate obtained was recovered by filtration obtaining a solid. The solid was dissolved in dichloromethane (Aldrich) (200 ml) and the solution obtained was placed in a 500 ml separating funnel: the whole was extracted with a saturated sodium bicarbonate solution (Aldrich) (3?100 ml) obtaining an acidic aqueous phase and an organic phase. The entire organic phase (obtained by combining the organic phases deriving from the three extractions) was washed to neutral with distilled water (3?50 ml) and subsequently anhydrified on sodium sulphate (Aldrich) and evaporated obtaining a solid which was further purified by crystallization with ethyl acetate (Aldrich). The crystals obtained were collected by filtration obtaining 6.57 g of 2,5-dibromobenzene-1,4-dicarbaldehyde having formula (VII) (yield 75%).

Example 4

Preparation of bis(2-octyldodecyl)anthra[1,2-b:5,6-b]dithiophene-4,10-dicarboxylate Having Formula (VIII)

[0122] ##STR00027##

[0123] In a 100 ml flask, fitted with magnetic stirrer, thermometer and refrigerant, in an inert atmosphere, to a mixture of 3-thiopheneacetic acid (Aldrich) (0.312 g; 2 mmol), triphenylphosphine (Aldrich) (0.026 g; 0.1 mmol), palladium(II)acetate Pd(OAc).sub.2 (Aldrich) (0.112 g; 0.5 mmol) in N,N-dimethylformamide anhydrous (DMF) (Aldrich) (5 ml), it was added 2,5-dibromobenzene-1,4-dicarbaldehyde having formula (VII) obtained as described in Example 3 (0.292 g; 1 mmol) and potassium carbonate (K.sub.2CO.sub.3) (Aldrich) (0.691 g; 5 mmol): the resulting mixture was heated at 80? C. and kept under stirring, at said temperature, for 24 hours. Subsequently, 1-bromo-2-octyldodecane (Sunatech) (0.795 g; 2.2 mmol) was added in a single portion: the reaction mixture obtained was left, under stirring, at 80? C., for 24 hours. Subsequently, after cooling to room temperature (25? C.), the reaction mixture was placed in a 500 ml separating funnel: an ammonium chloride (NH.sub.4Cl) 0.1 (Aldrich) (3?100 ml) solution was added to said reaction mixture and the whole was extracted with ethyl acetate (Aldrich) (3?100 ml) obtaining an aqueous phase and an organic phase. The entire organic phase (obtained by combining the organic phases deriving from the three extractions) was separated and subsequently anhydrified on sodium sulphate (Aldrich) and evaporated. The residue obtained was purified by elution on a chromatographic column of silica gel [(eluent: n-heptane/ethyl acetate 98/2) (Carlo Erba)], obtaining 0.752 g of bis(2-octyldodecyl)anthra[1,2-b:5,6-b]dithiophene-4,10-dicarboxylate having formula (VIII) as a waxy yellow solid (yield 80%).

Example 5

Preparation of bis(2-octyldodecyl)-2,7-bis-(tributylstannyl)anthra[1,2-b:5,6-b]dithiophene-4,10-dicarboxylate Having Formula (IIa)

[0124] ##STR00028##

[0125] In a 250 ml flask, fitted with magnetic stirring, it was loaded, under argon flow, in this order: bis(2-octyldodecyl)anthra[1,2-b:5,6-b]dithiophene-4,10-dicarboxylate having formula (VIII) obtained as described in Example 4 (0.47 g; 0.5 mmol) and 40 ml of anhydrous tetrahydrofuran (THF) (Aldrich): the reaction mixture obtained was placed, at ?78? C., for about 10 minutes. Subsequently, 4.4 ml of a solution of lithium di-iso-propylamine(LDA) (Aldrich) were added by dripping in a mixture of tetrahydrofuran (THF) (Aldrich)/hexane (Aldrich) (1:1, v/v) 2.0 M (0.182 g; 1.7 mmoles): the reaction mixture obtained was maintained, at ?78? C., for 3 hours. Subsequently, 0.678 ml of tri-butyl tin chloride (Aldrich) (1.302 g; 4 mmoles) were added by dripping: the reaction mixture obtained was placed at ?78? C., for 30 minutes and, subsequently, at room temperature (25? C.), for 16 hours. Subsequently, the reaction mixture was placed in a 500 ml separating funnel: said reaction mixture was diluted with a 0.1 M sodium bicarbonate solution (Aldrich) (200 ml) and extracted with diethyl ether (Aldrich) (3?100 ml), obtaining an acid aqueous phase and an organic phase. The entire organic phase (obtained by combining the organic phases deriving from the three extractions) was washed to neutral with water (3?50 ml) and subsequently anhydrified on sodium sulphate (Aldrich) and evaporated. The residue obtained was purified by elution on a basic alumina chromatographic column (Aldrich) [(eluent: n-heptane) (Aldrich)], obtaining 0.607 g of bis(2-octyldodecyl)-2,7-bis-(tributylstannyl)-anthra[1,2-b:5,6-b]dithiophene-4,10-dicarboxylate having formula (IIa) as straw yellow oil (yield 80%).

Example 6

Preparation of Conjugated Anthradithiophene Terpolymer Having Formula (Ia)

[0126] ##STR00029##

[0127] In a 250 ml flask, fitted with magnetic stirring, thermometer and coolant, in an inert atmosphere, it was loaded in this order: bis(2-octyldodecyl)-2,7-bis(tributylstannyl)anthra[1,2-b:5,6-b]dithiophene-4,10-dicarboxylate having formula (IIa) obtained as described in Example 5 (1.517 g; 1.05 mmol), 100 ml of chlorobenzene (Aldrich), 1,3-bis(5-bromothiophen-2-yl)-5,7-bis(2-ethylhexyl)benzo[1,2-c:4,5-c]dithiophene-4,8-dione (Sunatech) (0.690 g; 0.90 mmoles), 4,7-bis(5-bromo-4-octylthiophene-2-yl)-5,6-difluorobenzo[c][1,2,5]thiadiazole (Sunatech) (0.072 g; 0.1 mmoles), tris(dibenzylideneacetone)dipalladium(0) [Pd.sub.2(dba).sub.3] (Aldrich) (0.018 g; 0.02 mmol) and tris(ortho-tolyl)phosphine [P(o-tol).sub.3] (Aldrich) (0.024 g; 0.08 mmol). Subsequently, the reaction mixture obtained was heated to reflux and kept under stirring for 18 hours: the colour of the reaction mixture turned purple after 3 hours and turned dark purple at the end of the reaction (i.e. after 18 hours). Subsequently, after cooling to room temperature (25? C.), the reaction mixture obtained was placed in methanol (Aldrich) (300 ml) and the precipitate obtained was subjected to sequential extraction in a Soxhlet apparatus with methanol (Aldrich), acetone (Aldrich), n-heptane (Aldrich), dichloromethane (Aldrich), finally, chloroform (Aldrich). The residue left inside the extractor was dissolved in chlorobenzene (50 ml) (Aldrich) at 80? C. The hot solution was precipitated in methanol (300 ml) (Aldrich). The obtained precipitate was collected and dried under vacuum at 50? C., for 16 hours, obtaining 1.4 g of a dark violet solid product (90% yield), corresponding to the conjugated anthradithiophenic terpolymer having formula (Ia).

[0128] Said solid product was subjected to determination of the molecular weight by Gel Permeation Chromatography (GPC) operating as described above, obtaining the following data: [0129] (M.sub.w)=38574 Dalton; [0130] (PDI)=2.0334.

[0131] The values of the optical band-gap, operating as described above, both in solution (E.sub.g.sup.opt.sub.solution), and on thin film (E.sub.g.sup.opt.sub.film) and the HOMO value were also determined: [0132] (?.sub.EDGE sol)=651 nm; [0133] (?.sub.EDGE film)=654 nm; [0134] E.sub.g.opt.sol=1.95 eV; [0135] E.sub.g.opt.film=1.91 eV; [0136] (HOMO)=?5.30 eV.

Example 7

Preparation of a Conjugated Anthradithiophene Terpolymer Having Formula (Ib)

[0137] ##STR00030##

[0138] In a 250 ml flask, fitted with magnetic stirring, thermometer and coolant, in an inert atmosphere, it was loaded in this order: bis(2-octyldodecyl)-2,7-bis(tributylstannyl)anthra[1,2-b:5,6-b]dithiophene-4,10-dicarboxylate having formula (IIa) obtained as described in Example 5 (1.517 g; 1.05 mmol), 100 ml of chlorobenzene (Aldrich), 1,3-bis(5-bromothiophen-2-yl)-5,7-bis(2-ethylhexyl)benzo[1,2-c:4,5-c]dithiophene-4,8-dione (Sunatech) (0.69 g; 0.9 mmoles), 2,2,2-trifluoroethyl-2,5-dibromothiophene-3-carboxylate having formula (VI) obtained as described in Example 2 (0.368 g; 0.1 mmol), tris(dibenzylideneacetone)dipalladium(0) [Pd.sub.2(dba).sub.3] (Aldrich) (0.018 g; 0.02 mmoles) and tris(ortho-tolyl)phosphine [P(o-tol).sub.3] (Aldrich) (0.024 g; 0.08 mmoles). Subsequently, the reaction mixture obtained was heated to reflux and kept, under stirring, for 18 hours: the colour of the reaction mixture turned purple after 3 hours and turned dark purple at the end of the reaction (i.e. after 18 hours). Subsequently, after cooling to room temperature (25? C.), the reaction mixture obtained was placed in methanol (Aldrich) (300 ml) and the precipitate obtained was subjected to sequential extraction in a Soxhlet apparatus with methanol (Aldrich), acetone (Aldrich), n-heptane (Aldrich), dichloromethane (Aldrich), finally, chloroform (Aldrich). The residue left inside the extractor was dissolved in chlorobenzene (50 ml) (Aldrich) at 80? C. The hot solution was precipitated in methanol (300 ml) (Aldrich). The obtained precipitate was collected and dried under vacuum at 50? C. for 16 hours, obtaining 1.384 g of a dark violet solid product (92% yield), corresponding to the conjugated anthradithiophenic terpolymer having formula (Ib).

[0139] Said solid product was subjected to determination of the molecular weight by Gel Permeation Chromatography (GPC) operating as described above, obtaining the following data: [0140] (M.sub.w)=45796 Dalton; [0141] (PDI)=1.8472.

[0142] The values of the optical band-gap, operating as described above, both in solution (E.sub.g.sup.opt.sub.solution), and on thin film (E.sub.g.sup.opt.sub.film) and the HOMO value were also determined: [0143] (?.sub.EDGE sol)=646 nm; [0144] (?.sub.EDGE film)=660 nm; [0145] E.sub.g.opt.sol=1.92 eV; [0146] E.sub.g.opt.film=1.88 eV; [0147] (HOMO)=?5.45 eV.

Example 8 (Comparative)

Solar Cell Comprising Regioregular poly-3-hexylthiophene (P3HT)

[0148] For this purpose, an inverted polymer solar cell was used, schematically represented in FIG. 7.

[0149] For this purpose, a polymer-based device was prepared on an ITO (indium-tin oxide) coated glass substrate (Kintec CompanyHong Kong), previously subjected to a cleaning procedure comprising a manual cleaning, rubbing with a lint-free cloth soaked in a detergent diluted with tap water. The substrate was then rinsed with tap water. Subsequently, the substrate was thoroughly cleaned using the following methods in sequence: ultrasonic baths in (i) distilled water plus detergent (followed by manual drying with a lint-free cloth); (ii) distilled water [followed by manual drying with a lint-free cloth]; (iii) acetone (Aldrich) and (iv) iso-propanol (Aldrich) in sequence. In particular, the substrate was placed in a beaker containing the solvent, placed in an ultrasonic bath, kept at 40? C., for a treatment of 10 minutes. After treatments (iii) and (iv), the substrate was dried with a compressed nitrogen flow.

[0150] Subsequently, the glass/ITO was further cleaned in an air plasma device (Tucano typeGambetti), immediately before proceeding to the next step.

[0151] The substrate thus treated was ready for the deposition of the cathodic buffer layer. For this purpose, the zinc oxide (ZnO) buffer layer was obtained starting from a 0.162 M solution of the complex [Zn.sup.2+]-ethanolamine (Aldrich) in butanol (Aldrich). The solution was deposited by rotation on the substrate operating at a rotation speed equal to 600 rpm (acceleration equal to 300 rpm/s), for 2 minutes and 30 seconds, and subsequently at a rotation speed equal to 1500 rpm, for 5 seconds. Immediately after deposition of the cathodic buffer layer, zinc oxide formation was obtained by thermally treating the device at 140? C., for 5 minutes, on a hot plate in ambient air. The cathodic buffer layer thus obtained had a thickness equal to 30 nm and was partially removed from the surface with 0.1 M acetic acid (Aldrich), leaving the layer only on the desired surface.

[0152] The active layer, comprising regioregular poly-3-hexylthiophene (P3HT) (Plexcore OS) and methyl ester of the [6,6]-phenyl-C.sub.61-butyric acid (PC61BM) (Aldrich), was deposited on the cathodic buffer layer thus obtained by spin coating of a 1:0.8 (v/v) solution in o-dichlorobenzene (Aldrich) with a P3HT concentration equal to 10 mg/ml which had been kept under stirring overnight, operating at a rotation speed of 300 rpm (acceleration equal to 255 rpm/s), for 90 seconds. The thickness of the active layer was found to be 250 nm.

[0153] On the active layer thus obtained, the anodic buffer layer was deposited, which was obtained by depositing molybdenum oxide (MoO.sub.3) (Aldrich) through a thermal process: the thickness of the anodic buffer layer was equal to 10 nm. A silver (Ag) anode, having a thickness equal to 100 nm, was deposited on the anodic buffer layer by vacuum evaporation, appropriately masking the area of the device in order to obtain an active area equal to 25 mm.sup.2.

[0154] The depositions of the anodic buffer layer and of the anode were carried out in a standard evaporation chamber under vacuum containing the substrate and two evaporation vessels equipped with a heating resistance containing 10 mg of molybdenum oxide (MoO.sub.3) in powder and 10 (Ag) silver shots (diameter 1 mm-3 mm) (Aldrich), respectively. The evaporation process was carried out under vacuum, at a pressure of about 1?10.sup.?6 bar. The molybdenum oxide (MoO.sub.3) and silver (Ag), after evaporation, are condensed in the unmasked parts of the device.

[0155] The thicknesses were measured with a Dektak 150 (Veeco Instruments Inc.) profilometer.

[0156] The electrical characterization of the device obtained was carried out in a controlled atmosphere (nitrogen) in a glove box, at room temperature (25? C.). The current-voltage curves (I-V) were acquired with a Keithley? 2600A multimeter connected to a personal computer for data collection. The photocurrent was measured by exposing the device to the light of an ABET SUN? 2000-4 solar simulator, capable of providing 1.5G AM radiation with an intensity equal to 100 mW/cm.sup.2 (1 sun), measured with an Ophir Nova? II powermeter connected to a 3A-P thermal sensor. The device, in particular, is masked before said electrical characterization, so as to obtain an effective active area equal to 16 mm.sup.2: Table 2 shows the four characteristic parameters as average values.

Example 9 (Disclosure)

Solar Cell Disclosure Comprising the Conjugated Anthradithiophene Terpolymer Having Formula (Ia)

[0157] A polymer-based device was prepared on an ITO (indium-tin oxide) coated glass substrate (Kintec CompanyHong Kong), previously subjected to a cleaning procedure operating as described in Example 8.

[0158] The deposition of the cathodic buffer layer and the deposition of the anodic buffer layer were carried out as described in Example 8; the composition of said cathodic buffer layer and the composition of said anodic buffer layer are the same as the ones in Example 8; the thickness of said cathodic buffer layer and the thickness of said anodic buffer layer are the same as the ones in Example 8.

[0159] The active layer, comprising the conjugated anthradithiophene terpolymer having formula (Ia) obtained as described in Example 6 and the methyl ester of [6.6]-phenyl-C.sub.61-butyric acid (PC61BM) (Aldrich), was deposited on the cathodic buffer layer thus obtained by spin coating of a 1/1 (v/v) solution in o-xylene (Aldrich) with a concentration of conjugated anthradithiophene terpolymer having formula (Ia) equal to 10 mg/ml which had been kept at 100? C. under stirring overnight, operating at a rotation speed equal to 2000 rpm (acceleration equal to 2500 rpm/s), for 30 seconds. The thickness of the active layer was found to be 102 nm.

[0160] The deposition of the silver (Ag) anode was carried out as described in Example 8: the thickness of said silver anode (Ag) is the same as the one reported in Example 8.

[0161] The thicknesses were measured with a Dektak 150 (Veeco Instruments Inc.) profilometer.

[0162] The electrical characterization of the obtained device was carried out as described in Example 8: Table 2 shows the four characteristic parameters as average values.

[0163] FIG. 1 shows the current-voltage curve (I-V) obtained [the abscissa shows the voltage in millivolts (mV); the ordinate shows the short-circuit current density (Jsc) in milliampere/cm.sup.2 (mA/cm.sup.2)].

Example 10 (Disclosure)

Solar Cell Comprising the Conjugated Anthradithiophene Terpolymer of Formula (Ia)

[0164] A polymer-based device was prepared on an ITO (indium-tin oxide) coated glass substrate (Kintec CompanyHong Kong), previously subjected to a cleaning procedure operating as described in Example 8.

[0165] The deposition of the cathodic buffer layer and the deposition of the anodic buffer layer were carried out as described in Example 8; the composition of said cathodic buffer layer and the composition of said anodic buffer layer are the same as the ones in Example 8; the thickness of said cathodic buffer layer and the thickness of said anodic buffer layer are the same as the ones in Example 8.

[0166] The active layer, comprising the conjugated anthradithiophene terpolymer having formula (Ia) obtained as described in Example 6 and 3,9-bis(2-methylene-((3-(1,1-dicyanomethylene)-6,7-difluoro)-indanone))-5,5,11,11-tetrakis(4-hexyl-phenyl)-dithiene[2,3-d:2,3-d]-s-indacene[1,2-b:5,6-b]dithiophene (IT-4F) (Ossila), was deposited on the cathodic buffer layer thus obtained by spin coating of a 1:1 (v:v) solution in o-dichlorobenzene (Aldrich) with a concentration of anthradithiophenic conjugated terpolymer having formula (Ia) equal to 10 mg/ml which had been kept under stirring at 100? C. overnight, operating at a rotation speed equal to 2000 rpm (acceleration equal to 2500 rpm/s), for 30 seconds. The thickness of the active layer was found to be 102 nm.

[0167] The deposition of the silver (Ag) anode was carried out as described in Example 8: the thickness of said silver anode (Ag) is the same as the one reported in Example 8.

[0168] The thicknesses were measured with a Dektak 150 (Veeco Instruments Inc.) profilometer.

[0169] The electrical characterization of the obtained device was carried out as described in Example 8: Table 2 shows the four characteristic parameters as average values.

[0170] FIG. 2 shows the current-voltage curve (I-V) obtained [the abscissa shows the voltage in millivolts (mV); the ordinate shows the short-circuit current density (Jsc) in milliampere/cm.sup.2 (mA/cm.sup.2)].

[0171] FIG. 5 shows the curve relating to the External Quantum Efficiency (EQE) which was recorded under a monochromatic light (obtained using the TMc300F-U (I/C)Triple grating monochromator and a double source with a Xenon lamp and a halogen lamp with quartz) in an instrument from Bentham Instruments Ltd [the abscissa shows the wavelength in nanometres (nm); the ordinate shows the External Quantum Efficiency (EQE) in percent (%)].

Example 11 (Disclosure)

Solar cell Comprising the Conjugated Anthradithiophene Terpolymer of Formula (Ia)

[0172] A polymer-based device was prepared on an ITO (indium-tin oxide) coated glass substrate (Kintec CompanyHong Kong), previously subjected to a cleaning procedure operating as described in Example 8.

[0173] The deposition of the cathodic buffer layer and the deposition of the anodic buffer layer were carried out as described in Example 8; the composition of said cathodic buffer layer and the composition of said anodic buffer layer are the same as the ones in Example 8; the thickness of said cathodic buffer layer and the thickness of said anodic buffer layer are the same as the ones in Example 8.

[0174] The active layer comprising the conjugated anthradithiophene terpolymer having formula (Ia) obtained as described in Example 6 and 2,2-((2Z,2Z)-((4,4,9,9-tetrahexyl-4,9-dihydro-s-indacene[1,2-b:5,6-b]dithiophene-2,7- diyl)bis(methanilidene))bis(3-oxo-2,3-dihydro-1H-indene-2,1-diylidene))dimalononitrile (IDIC) (Sunatech) was deposited on the cathodic buffer layer thus obtained by spin coating of a 1:1 (v:v) solution in o-dichlorobenzene (Aldrich) with a concentration of conjugated anthradithiophene terpolymer having formula (Ia) equal to 9 mg/ml that had been kept at 100? C. under stirring overnight, operating at a rotation speed equal to 2000 rpm (acceleration equal to 2500 rpm/s), for 30 seconds. The thickness of the active layer was found to be 102 nm.

[0175] The deposition of the silver (Ag) anode was carried out as described in Example 8: the thickness of said silver anode (Ag) is the same as the one reported in Example 8.

[0176] The thicknesses were measured with a Dektak 150 (Veeco Instruments Inc.) profilometer.

[0177] The electrical characterization of the obtained device was carried out as described in Example 8: Table 2 shows the four characteristic parameters as average values.

[0178] FIG. 3 shows the current-voltage curve (J-V) obtained [the abscissa shows the voltage in millivolts (mV); the ordinate shows the short circuit current density (Jsc) in milliampere/cm.sup.2 (mA/cm.sup.2)].

Example 12 (Disclosure)

Solar Cell Comprising the Conjugated Anthradithiophene Terpolymer Having Formula (Ib)

[0179] A polymer-based device was prepared on an ITO (indium-tin oxide) coated glass substrate (Kintec CompanyHong Kong), previously subjected to a cleaning procedure operating as described in Example 8.

[0180] The deposition of the cathodic buffer layer and the deposition of the anodic buffer layer were carried out as described in Example 8; the composition of said cathodic buffer layer and the composition of said anodic buffer layer are the same as the ones in Example 8; the thickness of said cathodic buffer layer and the thickness of said anodic buffer layer are the same as the ones in Example 8.

[0181] The active layer, comprising the conjugated anthradithiophene terpolymer having formula (Ib) obtained as described in Example 7 and 3,9-bis(2-methylene-((3-(1,1-dicyanomethylene)-6,7-difluoro)-indanone))-5,5,11,11-tetrakis(4-hexyl-phenyl)-dithiene[2,3-d:2,3-d]-s-indacene[1,2-b:5,6-b]dithiophene (IT-4F) (Ossila), was deposited on the cathodic buffer layer thus obtained by spin coating of a 1:1 (v:v) solution in o-dichlorobenzene (Aldrich) with a concentration of anthradithiophenic conjugated terpolymer having formula (Ib) equal to 10 mg/ml which had been kept under stirring at 100? C. overnight, operating at a rotation speed equal to 2000 rpm (acceleration equal to 2500 rpm/s), for 30 seconds. The thickness of the active layer was found to be 102 nm.

[0182] The deposition of the silver (Ag) anode was carried out as described in Example 8: the thickness of said silver anode (Ag) is the same as the one reported in Example 8.

[0183] The thicknesses were measured with a Dektak 150 (Veeco Instruments Inc.) profilometer.

[0184] The electrical characterization of the obtained device was carried out as described in Example 8: Table 2 shows the four characteristic parameters as average values.

[0185] FIG. 4 shows the current-voltage curve (I-V) obtained [the abscissa shows the voltage in millivolts (mV); the ordinate shows the short circuit current density (Jsc) in milliampere/cm.sup.2 (mA/cm.sup.2)].

[0186] FIG. 6 shows the curve relating to the External Quantum Efficiency (EQE) which was recorded under a monochromatic light (obtained using the TMc300E-U (I/C)Triple grating monochromator and a double source with a Xenon lamp and a halogen lamp with quartz) in an instrument from Bentham Instruments Ltd [the abscissa shows the wavelength in nanometres (nm); the ordinate shows the External Quantum Efficiency (EQE) in percent (%)].

TABLE-US-00002 TABLE 2 V.sub.OC.sup.(2) J.sub.SC.sup.(3) PCE.sub.av.sup.(4) EXAMPLE FF.sup.(1) (V) (mA/cm.sup.2) (%) 8 (comparative) 0.57 0.56 10.10 3.30 9 (disclosure) 0.61 0.86 8.31 4.37 10 (disclosure) 0.63 0.86 15.69 8.52 11 (disclosure) 0.72 0.92 12.35 8.09 12 (disclosure) 0.49 0.86 15.13 6.40 .sup.(1)FF (Fill Factor) is calculated according to the following equation: [00001]$\frac{V_{\mathrm{MPP}}.Math.J_{\mathrm{MPP}}}{V_{\mathrm{OC}}.Math.J_{\mathrm{SC}}}$wherein V.sub.MPP and J.sub.MPP are voltage and current density, respectively, corresponding to the point of maximum power, V.sub.OC is the open circuit voltage and J.sub.SC is the short circuit current density; .sup.(2)V.sub.OC is the open circuit voltage; .sup.(3)J.sub.SC is the short circuit current density; .sup.(4)PCE.sub.av is the device efficiency calculated according to the following equation: [00002]$\frac{V_{\mathrm{OC}}.Math.J_{\mathrm{SC}}.Math.\mathrm{FF}}{P_{\mathrm{in}}}$wherein V.sub.OC, J.sub.SC and FF have the same meanings reported above and P.sub.in is the intensity of the incident light on the device.