Organic dye having general formula: X- n -Y- n -Z wherein: - X and Z, equal to or different from each other, represent a hydrogen atom; or are selected from the following groups: a -COOH group, a carboxycyanovinylene group having formula or: wherein R 2 and R 3, equal to or different from each other, represent an hydrogen atom, or are selected from C 1 -C 16 alkyl groups linear or branched; with the provision that at least one of X and Z is not an hydrogen atom; - T represents a 2,5-thienylene group having general formula: wherein R 4 and R 5, equal to or different from each other, represent an hydrogen atom; or are selected from: C 4 -C 20 alkyl groups, linear or branched, saturated or unsaturated, optionally containing heteroatoms, C 4 -C 12 cycloalkyl groups, optionally substituted, C 4 -C 11 heterocyclic groups, optionally substituted, C 3 -C 20 trialkylsilyl groups; with the provision that at least one of R 4 and R 5 is not an hydrogen atom; - n is an integer ranging from 2 to 7; - Y represents a divalent organic aromatic or heteroaromatic group having electron-donor properties selected from the groups having general formulae,,, (VIII),,,,, (XIII),,,, (XVII), (XVIII),: wherein R 6, R 7, R 8, R 9 and R 10, equal to or different from each other, represent an hydrogen atom; or are selected from: C 1 -C 30 alkyl groups, linear or branched, saturated or unsaturated, C 4 -C 12 cycloalkyl groups optionally substituted; said Y groups having general formulae - being optionally substituted with one or more groups selected from C 1 -C 30 alkyl groups, linear or branched, saturated or unsaturated, C 4 -C 12 cycloalkyl groups optionally substituted. - X and Z, equal to or different from each other, represent a hydrogen atom; or are selected from the following groups: a -COOH group, a carboxycyanovinylene group having formula or: wherein R 2 and R 3, equal to or different from each other, represent an hydrogen atom, or are selected from C 1 -C 16 alkyl groups linear or branched; with the provision that at least one of X and Z is not an hydrogen atom; - T represents a 2,5-thienylene group having general formula: wherein R 4 and R 5, equal to or different from each other, represent an hydrogen atom; or are selected from: C 4 -C 20 alkyl groups, linear or branched, saturated or unsaturated, optionally containing heteroatoms, C 4 -C 12 cycloalkyl groups, optionally substituted, C 4 -C 11 heterocyclic groups, optionally substituted, C 3 -C 20 trialkylsilyl groups; with the provision that at least one of R 4 and R 5 is not an hydrogen atom; - n is an integer ranging from 2 to 7; - Y represents a divalent organic aromatic or heteroaromatic group having electron-donor properties selected from the groups having general formulae,,, (VIII),,,,, (XIII),,,, (XVII), (XVIII),: wherein R 6, R 7, R 8, R 9 and R 10, equal to or different from each other, represent an hydrogen atom; or are selected from: C 1 -C 30 alkyl groups, linear or branched, saturated or unsaturated, C 4 -C 12 cycloalkyl groups optionally substituted; said Y groups having general formulae - being optionally substituted with one or more groups selected from C 1 -C 30 alkyl groups, linear or branched, saturated or unsaturated, C 4 -C 12 cycloalkyl groups optionally substituted.