Anthradithiophene derivatives, process for the preparation thereof and polymers that contain them

Abstract

An Anthradithiophene derivative having general formula (I): ##STR00001##
can be advantageously used in the synthesis of electron donor polymers These polymers can be advantageously used in the construction of photovoltaic devices (or solar devices) such as, for example, photovoltaic cells (or solar cells), photovoltaic modules (or solar modules), either on a rigid support or on a flexible support. Furthermore, these polymers can be advantageously used in the construction of Organic Thin Film Transistors (OTFTs), or Organic Field Effect Transistors (OFETs), or Organic Light-Emitting Diodes (OLEDs).

Claims

1. An Anthradithiophene derivative having general formula ##STR00035## wherein: Z, mutually identical or different, represent a sulfur atom, an oxygen atom, and/or a selenium atom; Y, mutually identical or different, represent a sulfur atom, an oxygen atom, and/or a selenium atom; R.sub.1 mutually identical or different, is selected from —N—R.sub.3R.sub.4 amino groups wherein R.sub.3 represents a hydrogen atom, or is selected from linear or branched C.sub.1-C.sub.20 alkyl groups, or is selected from optionally substituted cycloalkyl groups and R.sub.4 is selected from linear or branched C.sub.1-C.sub.20 alkyl groups, or is selected from optionally substituted cycloalkyl groups; or R.sub.1 is selected from linear or branched C.sub.1-C.sub.30 alkoxy groups; R.sub.1 is selected from R.sub.5—O—[CH.sub.2—CH.sub.2—O]n-polyethyleneoxy groups, wherein R.sub.5 is selected from linear or branched C.sub.1-C.sub.20 alkyl groups and n is an integer ranging from 1 to 4; or R.sub.1 is selected from —R.sub.6—OR.sub.7 groups, wherein R.sub.6 is selected from linear or branched C.sub.1-C.sub.20 alkylene groups and R.sub.7 represents a hydrogen atom, or is selected from linear or branched C.sub.1-C.sub.20 alkyl groups, or is selected from R.sub.5-[—OCH.sub.2—CH.sub.2]n-polyethyleneoxy groups, wherein n is an integer ranging from 1 to 4; or R.sub.1 is selected from —S—R.sub.8 thiol groups, wherein R.sub.8 is selected from linear or branched C.sub.1-C.sub.20 alkyl groups; or R.sub.1 is selected from —O—R′.sub.8 groups wherein R′.sub.8 is selected from optionally substituted aryl groups or optionally substituted heteroaryl groups; R.sub.2, mutually identical or different represent a hydrogen atom; or R.sub.2 is selected from linear or branched C.sub.1-C.sub.20 alkyl groups; or R.sub.2 is selected from —COR.sub.9 groups wherein R.sub.9 is selected from linear or branched C.sub.1-C.sub.20 alkyl groups; or R.sub.2 is selected from —COOR.sub.10 groups wherein R.sub.10 is selected from linear or branched C.sub.1-C.sub.20 alkyl groups; or R.sub.2 is selected from optionally substituted aryl groups; or R.sub.2 is selected from optionally substituted heteroaryl groups.

2. The a Anthradithiophene derivative having the general formula (I) according to claim 1, wherein in the general formula (I): Z, mutually identical, represent a sulfur atom; Y, mutually identical, represent an oxygen atom; R.sub.1, mutually identical, represent a C.sub.1-C.sub.30 alkoxy group; R.sub.2, mutually identical, represent a hydrogen atom.

3. A process for a preparation of an anthradithiophene derivative having general formula (I): ##STR00036## Z, mutually identical or different, represent a sulfur atom, an oxygen atom, and/or selenium atom; Y, mutually identical or different, represent a sulfur atom, an oxygen atom, and/or a selenium atom; R.sub.1 mutually identical or different, is selected from —N—R.sub.3R.sub.4 amino groups wherein R.sub.3 represents a hydrogen atom, or is selected from linear or branched C.sub.1-C.sub.20 alkyl groups, or is selected from optionally substituted cycloalkyl groups and R.sub.4 is selected from linear or branched C.sub.1-C.sub.20 alkyl groups, or is selected from optionally substituted cycloalkyl groups; or R.sub.1 is selected from linear or branched C.sub.1-C.sub.30 alkoxy groups; or R.sub.1 is selected from R.sub.5—O—[CH.sub.2—CH.sub.2—O]n-polyethyleneoxy groups, wherein R.sub.5 is selected from linear or branched C.sub.1-C.sub.20 alkyl groups and n is an integer ranging from 1 to 4; or R.sub.1 is selected from —R.sub.6—OR.sub.7 groups, wherein R.sub.6 is selected from linear or branched C.sub.1-C.sub.20 alkylene groups and R.sub.7 represents a hydrogen atom, or is selected from linear or branched C.sub.1-C.sub.20 alkyl groups, or is selected from R.sub.5-[—OCH.sub.2—CH.sub.2-]n-polyethyleneoxy groups, wherein R.sub.5 is selected from linear or branched C.sub.1-C.sub.20 alkyl groups and n is an integer ranging from 1 to 4; or R.sub.1 is selected from —S—R.sub.8 thiol groups, and wherein R.sub.8 is selected from linear or branched C.sub.1-C.sub.20 alkyl groups; or R.sub.1 is selected from —O—R′.sub.8 groups wherein R′.sub.8 is selected from optionally substituted aryl groups or optionally substituted heteroaryl groups; and R.sub.2, mutually identical, represent a hydrogen atom, comprising the following steps: (a) reacting at least one dihalogenated aryl compound having general formula (II): ##STR00037## wherein R.sub.11 is selected from linear or branched C.sub.1-C.sub.20 alkyl groups, and X represents a halogen atom selected from bromine, iodine, chlorine, fluorine with at least one halogenating agent, in the presence of ultraviolet radiation, obtaining a compound having general formula (III): ##STR00038## wherein X represents a halogen atom selected from bromine, iodine, chlorine, fluorine with at least one halogenating agent, and X.sub.1 represents a halogen atom selected from bromine, iodine, chlorine, fluorine; (b) reacting the compound having the general formula (III) obtained in step (a) with at least one silver-based oxidizing agent obtaining a compound having general formula (IV): ##STR00039## wherein X represents a halogen atom selected from bromine, iodine, chlorine, fluoride with at least one halogenating agent; (c) reacting the compound having the general formula (IV) obtained in step (b) with at least one heteroaryl compound having general formula (V): ##STR00040## wherein Z and Y, mutually identical or different, represent a sulfur atom, an oxygen atom, and/or a selenium atom, and at least one alkyl halide having general formula (VI):
X—R.sub.1  (VI) wherein X represents a halogen atom selected from bromine, iodine, chlorine, fluorine with at least one halogenating agent and R.sub.1 mutually identical or different, is selected from —N—R.sub.3R.sub.4 amino groups wherein R.sub.3 represents a hydrogen atom, or is selected from linear or branched C.sub.1-C.sub.20 alkyl groups, or is selected from optionally substituted cycloalkyl groups reported above, obtaining an anthradithiophene derivative having the general formula (I).

4. The process for the preparation of the anthradithiophene derivative having the general formula (I) according to claim 3, wherein: in said step (a) the halogenating agent is selected from bromine, iodine, chlorine, fluorine; and/or in said step (a) the dihalogenated aryl compound having the general formula (II) and the halogenating agent, are used in molar ratios ranging from 1:2 to 1:10; and/or in said step (a) the ultraviolet radiations have a wavelength ranging from 200 nm to 500 nm; and/or said step (a) is carried out in the presence of at least one halogenated organic solvent, the halogenated organic solvent being selected from chloroform (CHCI.sub.3), dichloromethane (CH.sub.2Cl.sub.2), carbon tetrachloride (CCI.sub.4), or mixtures thereof; and/or in said step (a) the dihalogenated aryl compound having the general formula (II) is used in the halogenated organic solvent at a molar concentration ranging from 0.05 mmol/ml to 2 mmol/ml; and/or said step (a) is carried out at a temperature ranging from 40° C. to 130° C.; and/or said step (a) is carried out for a time ranging from 30 minutes to 12 hours; and/or in said step (b) the silver-based oxidizing agent is selected from silver(I)-nitrate (AgNO.sub.3), silver(I)chloride (AgCI); and/or in said step (b) the compound having the general formula (III) and the oxidizing agent are used in molar ratios ranging from 1:3 to 1:20; and/or said step (b) is carried out in the presence of at least one protic or aprotic organic solvent, the protic organic solvent being selected from water (H.sub.2O), ethanol (EtOH), methanol, chloroform (CH.sub.3CI), acetonitrile (CH.sub.3CN), N,N-dimethylformamide (DMF), N-methyl-2-pyrrolidone (NMP), dichloromethane (DCM), or mixtures thereof; and/or in said step (b) the compound having the formula (III) is used in the protic or aprotic organic solvent at a molar concentration ranging from 0.05 mmol/l to 2 mmol/I; and/or said step (b) is carried out at a temperature ranging from 60° C. to 140° C.; and/or said step (b) is carried out for a time ranging from 30 minutes to 12 hours; and/or in said step (c) the compound having the general formula (IV) and the heteroaryl compound having the general formula (V) are used in molar ratios ranging from 1:0.3 to 1:10; and/or in said step (c) the compound having the general formula (IV) and the alkyl halide having the general formula (VI) are used in molar ratios ranging from 1:2 to 1:10; and/or said step (c) is carried out in the presence of at least one dipolar aprotic organic solvent, the dipolar aprotic organic solvent being selected from N,N-dimethylacetamide (DMAc), dimethylsulfoxide (DMSO), N-methyl-2-pyrrolidone (NMP), N,N-dimethylformamide (DMF), or mixtures thereof; and/or in said step (c) the compound having the general formula (IV) is used in the dipolar aprotic organic solvent at a molar concentration ranging from 0.05 mmol/I to 2 mmol/I; and/or said step (c) is carried out in the presence of a weak organic base, the weak organic base being selected from alkali or alkaline-earth metal carboxylates; alkali or alkaline-earth metal carbonates; bicarbonates of alkali or alkaline-earth metals; or mixtures thereof; and/or the compound having the general formula (IV) and the weak organic base are used in molar ratios ranging from 1:3 to 1:5; and/or said step (c) is carried out in the presence of at least one catalyst containing palladium, the catalyst containing palladium being selected from palladium complexes wherein the palladium is in oxidation state (0) or (II) such as bis-(triphenylphosphine)palladium(II) chloride [Pd(PPh.sub.3).sub.2CI.sub.2], bis(triphenyl-phosphine)palladium(II)acetate [Pd(PPh.sub.3).sub.2(OAc).sub.2], tetrakis(triphenyl-phosphine)palladium(0)acetate [Pd(PPh.sub.3).sub.4], bis(dibenzylidene)palladium(0) [Pd(dba).sub.2 wherein dba=C.sub.6H.sub.5CH═CHCOCH═CHC.sub.6H.sub.5], bis(acetonitrile)-palladium(II) chloride [Pd(CH.sub.3CN).sub.2CI.sub.2], benzyl[bis(triphenylphosphine)-palladium(II) chloride [C.sub.6H.sub.5CH.sub.2Pd(PPh.sub.3).sub.2CI], or mixtures thereof; and/or the compound having the general formula (IV) and the catalyst containing palladium are used in molar ratios ranging from 10:1 to 10:6; and/or said step (c) is carried out at a temperature ranging from 40° C. to 170° C.; and/or said step (c) is carried out for a time ranging from 30 minutes to 72 hours.

5. A process for a preparation of an anthradithiophene derivative having general formula (I): ##STR00041## wherein Z, mutually identical or different, represent a sulfur atom, an oxygen atom, a selenium atom; Y, mutually identical or different, represent a sulfur atom, an oxygen atom, a selenium atom; R.sub.1 mutually identical or different, is selected from —N—R.sub.3R.sub.4 amino groups wherein R.sub.3 represents a hydrogen atom, or is selected from linear or branched C.sub.1-C.sub.20 alkyl groups, or is selected from optionally substituted cycloalkyl groups and R.sub.4 is selected from linear or branched C.sub.1-C.sub.20 alkyl groups, or is selected from optionally substituted cycloalkyl groups; or R.sup.1 is selected from linear or branched C.sub.1-C.sub.30 alkoxy groups; or R.sub.1 is selected from R.sub.5—O—[CH.sub.2—CH.sub.2—O].sub.n-polyethyleneoxy groups, wherein R.sub.5 is selected from linear or branched C.sub.1-C.sub.20 alkyl groups and n is an integer ranging from 1 to 4; or R.sub.1 is selected from —R.sub.6—OR.sub.7 groups wherein R.sub.6 is selected from linear or branched C.sub.1-C.sub.20 alkylene groups and R.sub.7 represents a hydrogen atom, or is selected from linear or branched C.sub.1-C.sub.20 alkyl groups, or is selected from R.sub.5-[—OCH.sub.2—CH.sub.2].sub.n-polyethyleneoxy groups, wherein R.sub.5 is selected from linear or branched C.sub.1-C.sub.20 alkyl groups and n is an integer ranging from 1 to 4; or R.sub.1 is selected from —S—R.sub.8 thiol groups, wherein R.sub.8 is selected from linear or branched C.sub.1-C.sub.20 alkyl groups; or R.sub.1 is selected from —O—R′.sub.8 groups, wherein R′.sub.8 is selected from optionally substituted aryl groups or optionally substituted heteroaryl groups; R.sub.2, mutually identical or different represent a hydrogen atom; or R.sub.2 is selected from linear or branched C.sub.1-C.sub.20 alkyl groups; or R.sub.2 is selected from —COR.sub.9 groups, wherein R.sub.9 is selected from linear or branched C.sub.1-C.sub.20 alkyl groups; or R.sub.2 is selected from —COOR.sub.10 groups wherein R.sub.10 is selected from linear or branched C.sub.1-C.sub.20 alkyl groups; or R.sub.2 is selected from optionally substituted aryl groups; or R.sub.2 is selected from optionally substituted heteroaryl groups, provided that that R.sub.2, mutually identical or different, are different from a hydrogen atom, comprising the following steps: (d) reacting at least one dihalogenated dicarboxyl compound having the general formula (VII): ##STR00042## wherein X.sub.2 represents a halogen atom selected from bromine, iodine, chlorine, fluorine with at least one acylating agent, in the presence of at least one non-nucleophilic amine, and of at least one alkoxyalkylamine, obtaining a compound having general formula (VIII): ##STR00043## wherein R.sub.1 and X.sub.2 have the meanings reported above; (e) reacting the compound having the general formula (VIII) obtained in step (d) in the presence of at least one Grignard reagent obtaining an anthradithiophene derivative having the general formula (I).

6. The process according to claim 5, wherein: in said step (d) the acylating agent is selected from acetyl chloride, ethanoyl chloride, pentanoyl chloride, dodecanoyl chloride, trifluoroacetyl chloride, oxalyl chloride, phenylacetyl chloride, benzoyl chloride, or mixtures thereof; and/or in said step (d) the dicarboxylic dihalogenated compound having the general formula (VII) and the acylating agent are used in molar ratios ranging from 1:1 to 1:5; and/or in said step (d) the non-nucleophilic amine is selected from pyridine, 2,6-di-tert-butyl-4-methylpyridine, 2,4,6-trimethyl-pyridine, 2,4,6-tri-tert-butyl-pyridine, triethylamine (TEA), N-ethyl-di-iso-propylamine, 1,5-diazabicyclo(5.4.0)undec-7-ene (DBU), 1,4-diazabicyclo[2.2.2]octane (DABCO), or mixtures thereof; and/or in said step (d) the dihalogenated dicarboxylic compound having the general formula (VI) and the non-nucleophilic amine are used in molar ratios ranging from 1:1 to 1:5; and/or in said step (d), the alkoxyalkylamine is selected from methoxyethyl-amine, ethoxyethylamine, or mixtures thereof; and/or in said step (d), the dihalogenated dicarboxylic compound having the general formula (VII) and the alkoxyalkylamine are used in molar ratios ranging from 1:1 to 1:5; and/or said step (d) is carried out in the presence of at least one apolar organic solvent, the apolar organic solvent being selected from tetrahydrofuran (THF), diethyl ether, dioxane, toluene, or mixtures thereof; and/or in said step (d) the dihalogenated dicarboxylic compound having the general formula (VII) is used in the apolar organic solvent at a molar concentration ranging from 0.01 mmol/l to 2 mmol/l; said step (d) is carried out at a temperature ranging from −20° C. to 30° C.; and/or said step (d) is carried out for a time ranging from 30 minutes to 12 hours; and/or in said step (e) the Grignard reagent is selected from alkyl-magnesium halides having general formula (IX):
R.sub.12-MgX.sub.3  (IX) wherein R.sub.12 represents a linear or branched C.sub.1-C.sub.20 alkyl group, and X.sub.3 represents a halogen atom such as bromine, iodine, chlorine, fluorine; and/or in said step (e), the compound having the general formula (VIII) and the Grignard reagent are used in molar ratios ranging from 1:0.5 to 1:10; and/or said step (e) is carried out in the presence of at least one dipolar aprotic organic solvent, the dipolar aprotic organic solvent being selected from N,N-dimethylacetamide (DMAc), dimethylsulfoxide (DMSO), N-methyl-2-pyrrolidone (NMP), N,N-dimethylformamide (DMF), or mixtures thereof; and/or in said step (e) the compound having the general formula (VII) is used in the dipolar aprotic organic solvent at a molar concentration ranging from 0.05 mmol/l to 2 mmol/l; and/or said step (e) is carried out in the presence of a weak organic base, the weak organic base being selected from alkali or alkaline-earth metal carboxylates; alkali or alkaline-earth metal carbonates; bicarbonates of alkali or alkaline-earth metals; or mixtures thereof; and/or the compound having the general formula (VIII) and the weak organic base are used in molar ratios ranging from 1:3 to 1:5; and/or said step (e) is carried out in the presence of at least one catalyst containing palladium, the catalyst containing palladium being selected from palladium complexes wherein the palladium is in oxidation state (0) or (II) such as bis-(triphenylphosphine)palladium(II) chloride [Pd(PPh.sub.3).sub.2Cl.sub.2], bis(triphenyl-phosphine)palladium(II) acetate [Pd(PPh.sub.3).sub.2(OAc).sub.2], tetrakis(triphenyl-phosphine)palladium(0) acetate [Pd(PPh.sub.3).sub.4], bis(dibenzylidene)palladium(0) [Pd(dba).sub.2 wherein dba=C.sub.6H.sub.5CH═CHCOCH═CHC.sub.6H.sub.5], bis(acetonitrile)-palladium(II) chloride [Pd(CH.sub.3CN).sub.2Cl.sub.2], benzyl[bis(triphenylphosphine)palladium(II) chloride [C.sub.6H.sub.5CH.sub.2Pd(PPh.sub.3).sub.2Cl], or mixtures thereof; and/or the compound having the general formula (VIII) and the catalyst containing palladium are used in molar ratios ranging from 10:1 to 10:3; and/or said step (e) is carried out at a temperature ranging from 40° C. to 170° C.; and/or said step (e) is carried out for a time ranging from 30 minutes to 72 hours.

7. A polymer comprising an anthradithiophene derivative, the polymer having general formula (X): ##STR00044## wherein: Z, mutually identical or different, represent a sulfur atom, an oxygen atom, a selenium atom; Y, mutually identical or different, represent a sulfur atom, an oxygen atom, a selenium atom; R.sub.1 mutually identical or different, is selected from —N—R.sub.3R.sub.4 amino groups wherein R.sub.3 represents a hydrogen atom, or is selected from linear or branched C.sub.1-C.sub.20 alkyl groups, or is selected from optionally substituted cycloalkyl groups and R.sub.4 is selected from linear or branched C.sub.1-C.sub.20 alkyl groups, or is selected from optionally substituted cycloalkyl groups; or R.sub.1 is selected from linear or branched C.sub.1-C.sub.30 alkoxy groups; or R.sub.1 is selected from R.sub.5—O—[CH.sub.2—CH.sub.2—O].sub.n-polyethyleneoxy groups, wherein R.sub.5 is selected from linear or branched C.sub.1-C.sub.20 alkyl groups and n is an integer ranging from 1 to 4; or R.sub.1 is selected from —R.sub.6—OR.sub.7 groups wherein R.sub.6 is selected from linear or branched C.sub.1-C.sub.20 groups and R.sub.7 represents a hydrogen atom, or is selected from linear or branched C.sub.1-C.sub.20 alkyl groups, or is selected from R.sub.5-[—OCH.sub.2—CH.sub.2-].sub.n-polyethyleneoxy groups, wherein R.sub.5 is selected from linear or branched C.sub.1-C.sub.20 alkyl groups and n is an integer ranging from 1 to 4; or R.sub.1 is selected from —S—R.sub.8 thiol groups wherein R.sub.8 is selected from linear or branched C.sub.1-C.sub.20 alkyl groups; or R.sub.1 is selected from —O—R′.sub.8 groups, wherein R′.sub.8 is selected from optionally substituted aryl groups or optionally substituted heteroaryl groups; R.sub.2, mutually identical or different represent a hydrogen atom; or R.sub.2 is selected from linear or branched C.sub.1-C.sub.20 alkyl groups; or R.sub.2 is selected from —COR.sub.9 groups wherein R.sub.9 is selected from linear or branched C.sub.1-C.sub.20 alkyl groups; or R.sub.2 is selected from —COOR.sub.10 groups wherein R.sub.10 is selected from linear or branched C.sub.1-C.sub.20 alkyl groups; or R.sub.2 is selected from optionally substituted aryl groups; or R.sub.2 is selected from optionally substituted heteroaryl groups; A represents an electron-acceptor group; n is an integer ranging from 10 to 500.

8. A polymer according to claim 7, wherein in the general formula (X) the electron-acceptor group A is selected from the groups reported in the following Table 1: TABLE-US-00003 TABLE 1 wherein: B.sub.1 represents a sulfur atom, an oxygen atom, a selenium atom; or it represents an NR.sub.16 group wherein R.sub.16 represents a hydrogen atom, or is selected from linear or branched C.sub.1-C.sub.30 alkyl groups; Q.sub.1, mutually identical or different, represent a nitrogen atom, a sulfur atom, an oxygen atom, a selenium atom; or Q.sub.1 represents a C—R.sub.16 group, wherein R.sub.16 represents a hydrogen atom, or is selected from linear or branched c.sub.1-c.sub.30 alkyl groups; R.sub.13, mutually identical or different, is selected from linear or branched C.sub.1-C.sub.20 alkyl groups; optionally substituted cycloalkyl groups; optionally substituted aryl groups; optionally substituted heteroaryl groups; linear or branched C.sub.1-C.sub.20 alkoxyl groups; R.sub.17-[—OCH.sub.2—CH.sub.2-].sub.n-polyethyleneoxy groups wherein R.sub.17 is selected from linear or branched C.sub.1-C.sub.20 alkyl groups, and n is an integer ranging from 1 to 4; —R.sub.18—OR.sub.19 groups wherein R.sub.18 is selected from linear or branched C.sub.1-C.sub.20 alkylene groups, and R.sub.19 represents a hydrogen atom or is selected from linear or branched C.sub.1-C.sub.20 alkyl groups; —COR.sub.19 groups wherein R.sub.19 represents a hydrogen atom or is selected from linear or branched C.sub.1-C.sub.20 alkyl groups; —COOR.sub.19 groups wherein R.sub.19 represents a hydrogen atom or is selected from linear or branched C.sub.1-C.sub.20 alkyl groups above; or R.sub.19 represents a —CHO group, or a cyano group (—CN); R.sub.14 and R.sub.15, mutually identical or different, represent a hydrogen atom, a fluorine atom; or R.sub.14 and R.sub.15 is selected from linear or branched C.sub.1-C.sub.20 alkyl groups; optionally substituted cycloalkyl groups; optionally substituted aryl groups; linear or branched C.sub.1-C.sub.20 alkoxy groups; polyethyleneoxy groups R.sub.17-[—OCH.sub.2—CH.sub.2-].sub.n-wherein R.sub.17 is selected from linear or branched C.sub.1-C.sub.20 alkyl groups and n is an integer ranging from 1 to 4; R.sub.18—OR.sub.19 groups, wherein R.sub.18 is selected from linear or branched C.sub.1-C.sub.20 alkylene groups and R.sub.19 represent a hydrogen atom or is selected from linear or branched C.sub.1-C.sub.20 alkyl groups; —COR.sub.19 groups, wherein R.sub.19 represents a hydrogen atom or is selected from linear or branched C.sub.1-C.sub.20 alkyl groups; —COOR.sub.19 groups wherein R.sub.19 represents a hydrogen atom or is selected from linear or or branched C.sub.1-C.sub.20 alkyl groups; or R.sub.14 and R.sub.15 represent a —CHO group, or a cyano group (—CN); or, R.sub.14 and R.sub.15 can be linked to each other so as to form, together with the carbon atoms to which R.sub.14 and R.sub.15 are bonded, a cycle or a polycyclic system containing from 3 to 14 carbon atoms carbon atoms, saturated, unsaturated, or aromatic.

9. A photovoltaic device or solar device either on a rigid support or on a flexible support, the photovoltaic device comprising: at least one polymer having the general formula (X) according to claim 7.

10. An Organic Thin Film Transistors (OTFT), or Organic Field Effect Transistors (OFET), or Organic Light-Emitting Diode (OLED), comprising at least one polymer having one the general formula (X) according to claim 7.

11. The photovoltaic device of claim 9, wherein the photovoltaic device is selected from the group consisting of: a photovoltaic cell, a solar cell, a photovoltaic module, and a solar module.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 represents a cross-sectional view of a polymer photovoltaic cell (or solar cell) with an inverted structure.

(2) FIG. 2 shows a current-voltage curve (I-V) that was obtained according to the present disclosure.

(3) In FIG. 3 shows an External Quantum Efficiency (EQE) curve that was obtained according to the present disclosure.

EXAMPLES

(4) FIG. 1 below reported represent a cross-sectional view of a polymer photovoltaic cell (or solar cell) with an inverted structure used in the following Examples 7-8. With reference to FIG. 1, the polymer photovoltaic cell (or solar cell) with an inverted structure (1) comprises: a glass transparent support (7) a cathode (2) of indium tin oxide (ITO); a cathode buffer layer (3) comprising zinc oxide (ZnO); a layer of photoactive material (4) comprising regioregular poly(3-hexyltiophene) (P3HT) or a copolymer having general formula (X) and methyl ester of [6,6]-phenyl-C.sub.61-butyric acid (PC61BM); an anode buffer layer (5) comprising molybdenum oxide (MoO.sub.3); an anode (6) of silver (Ag).

(5) For the purpose of understanding the present invention better and to put it into practice, below are some illustrative and non-limiting examples thereof.

(6) Characterization of the polymers obtained

(7) Determination of the molecular weight

(8) The molecular weight of the polymers obtained operating according to the examples provided below, was determined through Gel Permeation Chromatography (GPC) on a WATERS 150C instrument, using HT5432 columns with, trichlorobenzene eluent, at 80° C.

(9) The weight average molecular weight (M.sub.w), the number average molecular weight (M.sub.n), the and the polydispersion index (PDI), corresponding to the M.sub.w/M.sub.n ratio, are reported.

(10) Determination of the optical band gap

(11) The polymers obtained operating according to the following examples, were characterized through UV-Vis-NIR spectroscopy to determine the amount of energy of the optical band gap in solution or on a thin film according to the following procedure.

(12) In the event that the optical band gap was measured in solution, the polymer was dissolved in toluene, chloroform, chlorobenzene, dichlorobenzene, trichlorobenzene, or another suitable solvent. The solution thus obtained was placed in a quartz cuvette and analyzed in transmission through a double beam UV-Vis-NIR spectrophotometer and Perkin Elmer double monochromator λ 950, in the range 200 nm-850 nm, with a pass band of 2.0 nm, scanning speed of 220 nm/min and step of 1 nm, using as a reference, an identical quartz cuvette containing only the solvent used as a reference.

(13) In the event that the optical band gap was measured on thin film, the polymer was dissolved in toluene, chloroform, chlorobenzene, dichlorobenzene, trichlorobenzene, or another suitable solvent, obtaining a solution having a concentration equal to about 10 mg/ml, which was deposited, through spin coating, on a Suprasil quartz slide. The thin film thus obtained was analyzed in transmission through a double beam UV-Vis-NIR spectrophotometer and Perkin Elmer double monochromator λ 950, in the range 200 nm-850 nm, with a pass band of 2.0 nm, scanning speed of 220 nm/min and step of 1 nm, using as a reference an identical Suprasil quartz slide, as such, as a reference.

(14) From the spectra in transmission the optical band gap was estimated by measuring the absorption corresponding to the transition from the valence band (VB) to the conduction band (CB). To determine the edge, the intersection with the axis of the abscissa of the straight line tangent to the absorption band in the inflexion point was used.

(15) The inflexion point (λ.sub.F, y.sub.F) was determined based on the coordinates of the minimum of the first derivative spectrum, indicated with λ′.sub.min and y′.sub.min.

(16) The equation of the straight line tangent to the UV-Vis spectrum in the inflexion point (λ.sub.F, y.sub.F) is as follows:
y=y′.sub.minλ+y.sub.F−y′.sub.minλ′.sub.min

(17) Finally, from the intersection condition with the axis of the abscissa ψ=0, the following was obtained:
λ.sub.EDGE=(y′.sub.minλ′.sub.min−y.sub.F)/y′.sub.min

(18) Therefore, by measuring the coordinates of the minimum of the first derivative spectrum and the corresponding absorbance value y.sub.F of the UV-Vis spectrum, λ.sub.EDGE was obtained directly by substitution.

(19) The corresponding energy is:
E.sub.EDGE=hν.sub.EDGE=h c/λ.sub.EDGE

(20) wherein: h=6.626 10-34 J s; c=2.998 108 m s.sup.−1,

(21) i.e.:
E.sub.EDGE=1.988 10-16 J/λ.sub.EDGE(nm).

(22) Remembering, finally, that 1 J=6.24 1018 eV, therefore:
E.sub.EDGE=1240 eV/λ.sub.EDGE(nm).

(23) Determination of HOMO and LUMO

(24) The determination of the HOMO and LUMO values of the polymers obtained by operating according to the following examples, was carried out through the cyclic voltammetry (CV) technique. With such technique it is possible to measure the values of the radical cation and radical anion formation potential in question. These values, entered into a relevant equation, allow HOMO and LUMO values of the polymer in question to be obtained. The difference between HOMO and LUMO provides the electrochemical band gap value.

(25) The electrochemical band gap values are generally higher than the optical band gap values as during the performance of the cyclic voltammetry (CV), the neutral compound is charged and undergoes a conformational reorganization, with an increase in the energy “gap”, while the optical measurement does not lead to the formation of charged species.

(26) The cyclic voltammetry (CV) measurements were carried out with an Autolab PGSTAT12 potentiostat (with GPES Ecochemie software) in a three-electrode cell. In the measurements carried out the reference electrode was an Ag/AgCI electrode, the counter-electrode a platinum wire and the working electrode a vitreous graphite electrode. The sample to be analyzed was dissolved in an appropriate solvent and, subsequently, was 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% tetrabutlyammonium tetrafluoroborate in acetonitrile. The sample was then subjected to a cyclic potential in the form of a triangular wave. Simultaneously, as a function of the difference in potential applied, the current was monitored, which signals the occurrence of oxidation or reduction reactions of the species present.

(27) The oxidation process corresponds to the removal of an electron from the HOMO, while the reduction cycle corresponds to the introduction of an electron into the LUMO. The radical cation and radical anion formation potentials were obtained from the value of the peak onset (E.sub.onset), which is determined by chain molecules and/or segments with closer HOMO-LUMO levels to the margins of the bands. The electrochemical potentials at those related to the electronic levels can be correlated if they both refer to vacuum. For this purpose, the potential of ferrocene in vacuum was taken as the reference, known in literature to be equal to −4.8 eV. The ferrocene/ferrocinium (Fc/Fc+) intersolvent redox couple was selected because it has an oxidation-reduction potential that is independent from the working solvent.

(28) The general formula for calculating the energy of the HOMO-LUMO levels therefore comes from the following equation:
E(eV)=−4.8+[E.sub.1/2 Ag/AgCl(Fc/Fc.sup.+)−E.sub.onset Ag/AgCl(polymer)]

(29) wherein: E=HOMO or LUMO according to the value of E.sub.onset entered; E.sub.1/2 Ag/AgCl=half wave potential of the peak corresponding to the ferrocene/ferrocinium redox couple measured under the same sample analysis conditions and with the same three electrodes used for the sample; E.sub.onset Ag/AgCl=onset potential measured for the polymer in the anode area when the HOMO is to be calculated and in the cathode area when the LUMO is to be calculated.

Example 1

Preparation of 1,4-dibromo-2,5-bis(dibromomethyl)benzene Having Formula (IIIa)

(30) ##STR00029##

(31) In a 100 ml flask, with a magnetic stirrer, thermometer and coolant, in an inert atmosphere, the following were loaded, in order: 1,4-dibromo-2,5-dimethylbenzene (Aldrich) (13.20 g; 50.0 mmoles) [dihalogenated acrylic compound having general formula (II) wherein R.sub.11=methyl and X=bromine] and carbon tetrachloride (Aldrich) (1590 ml) and, after heating to reflux temperature, for 5 minutes, a bromine solution (Aldrich) (10.80 ml; 210 mmoles) in carbon tetrachloride (Aldrich) (50 ml) was added, by dripping: the reaction mixture obtained was maintained at reflux temperature, under stirring, and subjected to radiation with an incandescent lamp at 500 W (UV radiation emitted at 300 nm), for 4 hours. Subsequently, after cooling to room temperature (25° C.), the reaction mixture obtained was placed in a 500 ml separator funnel: a concentrated aqueous solution of sodium bisulfite (NaHSO.sub.3) (Aldrich) (3×100 ml) and deionized water (Aldrich) (3×100 ml) was added to said reaction mixture and everything was extracted, obtaining an acidic aqueous phase and an organic phase. The entire organic phase (obtained by joining the organic phases deriving from the three extractions) was subsequently anhydrified on sodium sulfate (Aldrich) and evaporated. The residue obtained was recrystallized from ethyl acetate (Aldrich) (50 ml), obtaining 26.04 g of 1,4-dibromo-2,5-bis(dibromomethyl)benzene having formula (III) as white crystals (yield 89%).

Example 2

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

(32) ##STR00030##

(33) In a 100 ml flask, with a magnetic stirrer, thermometer and coolant, in an inert atmosphere, a solution of silver(l)nitrate (AgNO.sub.3) (Aldrich) (36.90 g, 217 mmol) in water (90 ml) was added to a suspension of 1,4-dibromo-2,5-bis(dibromomethyl)benzene having formula (III) obtained as described in Example 1 (18.0 g; 31 mmol) in acetonitrile (Aldrich) (600 ml): the reaction mixture obtained was maintained at reflux temperature, under stirring, for 5 hours. Subsequently, the reaction mixture was filtered while still hot and hot acetonitrile (500 ml) was added to the solid obtained, obtaining a mixture that was cooled to room temperature (25° C.) to allow crystallization. The crystals obtained were collected by filtration obtaining 9.16 g of 2,5-dibromobenzene-1,4-dicarbaldehyde having formula (IV) (yield 95%).

Example 3

Preparation of Bis(2-octyldodecyl)anthra[1,2-b:5,6-b′]dithiophene-4,10-dicarboxylate having Formula (Ia)

(34) ##STR00031##

(35) In a 100 ml flask, with a magnetic stirrer, thermometer and coolant, in an inert atmosphere, 2,5-dibromobenzene-1,4-dicarbaldehyde having formula (IV) obtained as described in Example 2 (0.292 g; 1.0 mmol) and potassium carbonate (K.sub.2CO.sub.3) (Aldrich) (0.691 g; 5.0 mmol) were added to a mixture of 3-thiopheneacetic acid [heteroaryl compound having general formula (V) wherein Y=oxygen and Z=sulfur] (Aldrich) (0.312 g; 2.2 mmol), triphenylphosphine (Aldrich) (0.026 g; 0.1 mmol), palladium(II)acetate [Pd(OAc).sub.2] (0.112 g; 0.5 mmol) in N,N-dimethylformamide anhydrous (DMF) (Aldrich) (5 ml): the resulting reaction mixture was heated to 80° C. and maintained under stirring, at said temperature, for 24 hours. Subsequently, 1-bromo-2-octyldodecane (Aldrich) [alkyl halide having general formula (VI) wherein R.sub.1=2-octyldodecyl and X=bromine] (0.672 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 separator funnel: a solution of ammonium chloride (NH.sub.4Cl) 0.1 M (Aldrich) (3×100 ml) was added to said reaction mixture and everything was extracted with ethyl acetate (Aldrich) (3×100 ml) obtaining an aqueous phase and an organic phase. The entire organic phase (obtained by joining the organic phases deriving from the three extractions) was separated and subsequently anhydrified on sodium sulfate (Aldrich) and evaporated. The residue obtained is purified through elution on a silica gel chromatography column [(eluent: n-heptane/ethylacetate 98/2) (Carlo Erba)], obtaining 0.083 g of bis(2-hexyldecyl)anthra[1,2-b:5,6-b′]dithiophene-4,10-dicarboxylate having formula (Ia) as a white solid (yield 10%).

Example 4

Preparation of Bis(2-octyldodecyl)-2,8-bis(tributylstannyl)anthra[1,2-b:5,6-b′]dithiophene-4,10-dicarboxylate Having Formula (XIa)

(36) ##STR00032##

(37) In a 100 ml flask, with a magnetic stirrer, the following were loaded in order, under a flow of argon: bis(2-ocytildodecyl)anthra[1,2-b:5,6-b]dithiophene-4,10-dicarboxylate having formula (Ia) (0.564 g; 0.600 mmoles) obtained as described in Example 3, and 25 ml of tetrahydrofuran (THF) anhydrous (Aldrich). The reaction mixture obtained was placed at −78° C. for about 10 minutes. Subsequently, 1.80 ml of a solution of lithium diisopropylamide (LDA) in a mixture of 1.0 M tetrahydrofuran (THF)/hexane (0.193 g; 1.8 mmoles) (Aldrich) were added by dripping: the reaction mixture obtained was maintained at −78° C., for 1 hour and, subsequently, at room temperature (25° C.), for 1 hour. Subsequently, 0.570 ml of tri-butyl tin chloride (0.684 g; 2.1 mmoles) were added by dripping: the reaction mixture obtained was placed at −78° C., for 15 minutes and, subsequently, at room temperature for 16 hours. Subsequently, the reaction mixture was placed in a 500 ml separator funnel: said reaction mixture was diluted with a 0.1 M solution of sodium bicarbonate (Aldrich) (200 ml) and extracted with diethyl ether (Aldrich) (3×100 ml) obtaining an acidic aqueous phase and an organic phase.

(38) The entire organic phase (obtained by joining the organic phases deriving from the three extractions) was washed to neutrality with water (3×50 ml) and subsequently anhydrified on sodium sulfate (Aldrich) and evaporated. The residue obtained is purified through elution on a basic alumina chromatography column (Aldrich) [(eluent: n-heptane/ethylacetate 99/1) (Carlo Erba)], obtaining 0.819 g of bis(2-octyldodecyl)-2,8-bis(tributylstannyl)anthra[1,2-b:5,6-b]dithiophene-4,10-dicarboxylate having formula (XIa) as a straw yellow oil (yield 90%).

Example 5

Preparation of the Copolymer Having Formula (Xa)

(39) ##STR00033##

(40) In a 100 ml flask, with a magnetic stirrer, thermometer and coolant, in an inert atmosphere, the following were loaded, in order: 4,7-dibromobenzo[c]-1,2,5-thiadiazole (Aldrich) (0.159 g; 0.540 mmol), 20 ml of toluene (Aldrich), bis(2-octyldodecyl)-2,8-bis(tributylstannyl)-anthra[1,2-b:5,6-b]dithiophene-4,10-dicarboxylate having formula (XIa) obtained as described in Example 4 (0.819 g; 0.540 mmoles), tris(dibenzylideneacetone)dipalladium(0) [Pd2(dba).sub.3] (Aldrich) (0.009 g; 0.011 mmol) and tris(o-tolyl)phosphine [P(o-tol).sub.3] (Aldrich) (0.033 g; 0.108 mmoles). Subsequently, the reaction mixture was heated to reflux temperature and maintained, under stirring, for 48 hours. The color of the reaction mixture turned purple after 3 hours and became dark purple at the end of the reaction (i.e. after 24 hours). Subsequently, after cooling to room temperature (25° C.), the reaction mixture obtained was placed in methanol (300 ml) and the precipitate obtained was subjected to sequential extraction in Soxhlet apparatus with methanol (Aldrich), acetone (Aldrich), n-heptane (Aldrich) and, finally, chloroform (Aldrich). The solution obtained was concentrated in a reduced atmosphere and precipitated in methanol (300 ml) (Aldrich). The precipitate obtained was collected and vacuum dried at 50° C., for 16 hours, obtaining 0.492 g of a solid dark purple product (yield 85%), corresponding to the copolymer having formula (Xa).

(41) Said solid product was subjected to the determination of the molecular weight through Gel Permeation Chromatography (GPC) operating as described above, obtaining the following data: (Mw)=41356 Dalton; (PDI)=2.0113.

(42) The optical band-gap values were also determined, 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: E.sub.g.sup.opt.sub.film=1.83 eV; E.sub.g.sup.opt.sub.solution=1.97 eV;

(43) HOMO=−5.75 eV.

Example 6

Preparation of the Copolymer Having Formula (Xb)

(44) ##STR00034##

(45) In a 100 ml flask, with a magnetic stirrer, thermometer and coolant, in an inert atmosphere, the following were loaded, in order: bis(2-octyldodecyl)-2,8-bis(tributylstannyl)-anthra[1,2-b:5,6-b′]dithiophene-4,10-dicarboxylate having formula (XIa) obtained as described in Example 4 (1.180 g; 0.777 mmoles), 75 ml of anhydrous toluene (Aldrich), 1,3-dibromo-5,7-bis(2-ethylhexyl)benzo[1,2-c:4,5-c′]-dithiophene-4,8-dione (Aldrich) (0.541 g; 0.706 mmol), tris(dibenzylideneacetone)-dipalladium(0) [Pd2(dba).sub.3] (Aldrich) (0.013 g; 0.014 mmol) and tris(o-tolyl)-phosphine [P(o-tol).sub.3] (Aldrich) (0.021 g; 0.071 mmoles). Subsequently, the reaction mixture was heated to reflux temperature and maintained, under stirring, for 18 hours. The color of the reaction mixture turned brick red after 3 hours and became dark purple at the end of the reaction (i.e. after 18 hours). Subsequently, after cooling at 60° C., the reaction mixture obtained was placed in methanol (300 ml) and the precipitate obtained was subjected to sequential extraction in Soxhlet apparatus with methanol (Aldrich), acetone (Aldrich), n-heptane (Aldrich), chloroform (Aldrich) and, finally, chlorobrenzene (Aldrich). The solution obtained was concentrated in a reduced atmosphere and precipitated in methanol (300 ml) (Aldrich). The precipitate obtained was collected and vacuum dried at 50° C., for 16 hours, obtaining 0.940 g of a solid dark purple product (yield 86%), corresponding to the copolymer having formula (Xb). Said solid product was subjected to the determination of the molecular weight through Gel Permeation Chromatography (GPC) operating as described above, obtaining the following data: (M.sub.w)=53383 Dalton; (PDI)=1.7996.

(46) The optical band-gap values were also determined, 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: E.sub.g.sup.opt.sub.film=1.90 eV; E.sub.g.sup.opt.sub.solution=1.91 eV; HOMO=−5.37 eV.

Example 7

Reference Cell

(47) A polymer photovoltaic cell (or solar cell) with an inverted structure represented in FIG. 1 was used.

(48) To this aim, a polymer based device was prepared on a ITO (Indium Tin Oxide) coated glass substrate (Kintec Company—Hong Kong), previously submitted to a cleaning procedure consisting in a manual cleaning, wiping with a lint-free cloth soaked with a detergent diluted in tap water. The substrates were then rinsed with tap water. Successively, the substrates were thoroughly cleaned according to 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 and (iv) iso-propanol in sequence. In particular, the substrates were arranged in a becker containing the solvent, located in a ultrasonic bath, kept at ambient temperature, for a 10 minutes treatment. After treatments (iii) and (iv), each substrate was dried with a compressed nitrogen flux. Subsequently, the glass/ITO was further cleaned in an air plasma cleaner (Tucano type—Gambetti), immediately before proceeding to the next stage. The so treated substrate was ready for the deposition of the cathode buffer layer of zinc oxide (ZnO). The cathode buffer layer of zinc oxide (ZnO) was obtained via a sol-gel process starting from the precursor solution prepared as disclosed in Example 1 of International Patent Application WO 2015/068102 in the name of the Applicant which is hereby incorporated by reference. The solution was spin-casted on the substrate rotating at 600 rpm for 150 sec, followed by rotating at 1500 rpm for 5 sec. Immediately after the layer deposition, the ZnO formation was obtained by thermally treating the device, at 140° C., for 5 min, on a hot plate, in ambient air. The so obtained layer had a thickness of 30 nm and it was partially removed with iso-propanol 0,1 M, leaving the layer only on the desired area. In order to obtain a correct deposition, the ambient temperature has to be ranging from 18° C. to 21° C. and the relative humidity of the ambient has to be ranging from 35% to 45%.

(49) The active layer, composed by poly-(3-hexylthiophene) (P3HT) and [6,6]-phenyl-C.sub.61-butyric acid methyl ester (P3HT:PC61BM), was spin-casted from a solution 1:0.8 (w/w) in chlorobenzene (Aldrich—purity=99%) with a P3HT concentration of 10 mg/ml, which was kept under stirring, at 50° C., overnight. The thin film was obtained by rotation at 300 rpm (acceleration 255 rpm/sec) for 90 sec. The thickness of the layer resulted to be 250 nm (measured on a test cell).

(50) Above the so obtained layer, a third layer was deposited, namely the anode buffer layer, which was obtained by depositing a commercial molybdenum oxide (MoO.sub.3) through thermic process: the thickness of the layer 10 nm. On top of the layer stack, a 100 nm thick silver (Ag) anode was evaporated, suitably masking the device area so as to obtain an active area of 25 mm.sup.2. The depositions of the two last layers were carried out in a standard thermal evaporation chamber containing the substrate and two resistance-heated evaporation vessels containing 10 mg of a molybdenum oxide (MoO.sub.3) in powder form and 10 silver (Ag) shots (diameter 1-3 mm), respectively. The evaporation process was carried out under vacuum at a pressure of about 1×10.sup.−6 bar. The evaporated molybdenum oxide (MoO.sub.3) and silver (Ag) condensed on the unmasked regions of the substrate. The thickness of the layers was measured with a profilometer Dektak 150 (Veeco Instruments Inc.). The electrical characterization of the device was performed, in ambient atmosphere, just the device construction was terminated.

(51) The current-voltage curves (I-V) were recorded with a multimeter Keithley® 2600A connected to a personal computer for data collection. Photocurrent was measured by exposing the device to the light of a ABET SUN® 2000-4 sun simulator, able to provide an AM 1.5 G irradiation with an intensity of 100 mW/cm.sup.2 (1 sun), measured with a Ophir Nova® II powermeter connected to a thermal sensor 3A-P. The device, in particular, was masked, so as to obtain an effective area equal to 0.16 mm.sup.2. In Table 2 the four characteristic parameters are reported as average values.

(52) The external quantum efficiency (EQE) curves were registered under a monochromatic light (obtained by a monochromator TMc300F-U (I/C)—Triple grating monochromator and a double source with a Xenon lamp and a halogen with quartz lamp) into a customized tool of Bentham Instrument Ltd. All the preparation stages, as well as the all the characterization measurements of the device, were not expressly mentioned, were carried out in air.

Example 8

Cell Containing Copolymer Having Formula (Xb)

(53) The substrate was cleaned as described for the reference sample (Example 7) and subsequently treated with air plasma.

(54) The substrate was then ready for the deposition of the cathode buffer layer of zinc oxide (ZnO), as described in Example 7, having a thickness of 30 nm. Subsequently, the active layer composed by copolymer having formula (Xb) obtained as described in Example 6 and [6,6]-phenyl-C.sub.61-butyric acid methyl ester (PC61BM) (copolymer having formula (Xb):PC61BM), was spin-casted from a solution 1:0.8 (w/w) in 1,2-dichlorobenzene (Aldrich—purity=99%) with a copolymer having formula (Xb) concentration of 6 mg/ml which was maintained, before spin-casting, under stirring, over a magnetic heating plate, at 130° C., overnight. The thin film was obtained by rotation at 950 rpm (acceleration 2500 rpm/sec) for 90 sec. The thickness of the layer resulted to be 60 nm (measured on a test cell). The remaining layers was deposited as described in Example 7.

(55) The electrical characterization of the device was performed, in ambient atmosphere, just the device construction was terminated, operating as described in Example 7: the obtained results are given in Table 2. In FIG. 2 was reported the current-voltage curve (I-V) obtained [in abscissa was reported the voltage in volts (V); in the ordinate was reported the short-circuit photocurrent density (J.sub.sc) in milliamperes/cm.sup.2 (mA/cm.sup.2)].

(56) In FIG. 3 was reported the External Quantum Efficiency (EQE) curve which was registered under a monochromatic light [obtained by a monochromator TMc300F-U (I/C)—Triple grating monochromator and double source with a Xenon lamp and a quartz halogen lamp] in an instrument of a Bentham Instruments Ltd. [in abscissa was reported the External Quantum Efficiency (EQE) in percent (EQE [%]; in the ordinate was reported the wavelength in nanometers (nm)].

(57) TABLE-US-00002 TABLE 1 Voc.sup.(2) J.sub.sc.sup.(3) PCE.sub.av.sup.(4) Example FF.sup.(1) (mV) (mA/cm.sup.2) (%) 7 (comparative) 0.57 0.56 11.10 3.30 8 (invention) 0.62 0.91 10.10 6.02 .sup.(1)FF (fill factor) calculated according to the following formula: $\frac{V_{\mathrm{MPP}}.Math.J_{\mathrm{MPP}}}{V_{\mathrm{OC}}.Math.J_{\mathrm{SC}}}$wherein V.sub.MPP and J.sub.MPP are current tension and current density corresponding to the point of maximum power, respectively, V.sub.OC is the open circuit voltage and J.sub.SC is short-circuit photocurrent density; .sup.(2)V.sub.OC is the open circuit voltage; .sup.(3)J.sub.SC is the short-circuit photocurrent density; .sup.(4)PCE.sub.av is the photoelectric conversion efficiency of the device calculated according to the following formula: $\frac{V_{\mathrm{OC}}.Math.J_{\mathrm{SC}}.Math.\mathrm{FF}}{P_{\mathrm{in}}}$wherein V.sub.OC, J.sub.SC and FF, have the same meanings reported above and P.sub.in is the intensity of the light incident on the device.