NOVELTY - Donor ridge acceptor of asymmetric cyanine dye (I), including its valence tautomer, is new.    USE - In dye sensitized solar cell (DSSC), photoelectric conversion device (claimed), and photonic device; as sensitizer for photoelectrochemical cells.    ADVANTAGE - The dyes have a broad absorption spectrum and very high extinction coefficients; and exhibits good performance in solar energy conversion in dye-based cells.    DETAILED DESCRIPTION - Donor ridge acceptor of asymmetric cyanine dye (D- pi -A dye) of formula (I), including its valence tautomer, is new.    X=C(CH3)2, -O, -S, -CH=CH, or H3C-(CH2)j-C-(CH2)k-CH3;    j=1-20;    k=1-20;    R'=-COOH, -OH, -C?=N, -CHO, -PO3H, -PO3-, -B(OH)2, -C(C?=N)-C(=O)-OH or R15-Y1-;    R15=linear or branched, saturated or unsaturated 3-30C alkyl chain, where each optionally replaced with component selected from an oxygen or sulfur, -NH-, -CONH-, cyclic aromatic or non-aromatic 4-, 5- or 6-membered grouping of carbon atoms (where at least one carbon atom is optionally replaced with a heteroatom selected from O, S, N or selenium;    Y1=N, carboxyl, carbonyl, amino, sulphydryl, thiocyanate, isothiocyanate, isocyanate, maleimide, hydroxyl, phosphoramidite, glycidyl, imidazolyl, carbamoyl, anhydride, bromoacetamide, chloroacetamide, iodoacetamide, sulfonyl halide, acyl halide, aryl halide, hydrazide, succinimidyl ester, hydroxysulfosuccinimidyl ester, phthalimidyl ester, naphthalimidyl ester, monochlorotriazine, dichlorotriazine, mono- or di- halo substituted pyridine, mono- or di-halo substituted diazine, aziridine, imidyl ester, hydrazine, azidonitrophenyl, azide, 3-(2-pyridyldithio)-propionamide, glyoxal, aldehyde, nitrophenyl, dinitrophenyl, trinitrophenyl or -Si(R1)(R12)(R13);    R11-R13=methyl, ethyl, propyl, isopropyl, -OCH3, -OCH2CH3, -OCH2CH2CH3, -OCH(CH3)2, -OCH2CH2OCH3, -Cl, -Br, -I, -N(CH3)2, -O-C(=O)-CH3, -O-C(=O)-CH2-CH3-NH-, substituted cyclohexyl-amine, or -O-N=C(CH3)2;    R'1=H, -COOH, -OH, -C?=N, -CHO, -PO3H, -PO3-, -B(OH)2, or R16-Y2;    R16=R15;    Y2=Y1;    G'=conjugated system or forms a conjugated system with the adjacent heterocyclic nucleus, where the conjugated system consisting of 2-200C, where at least one carbon atom is optionally replaced with a component selected from O, S, N, Si, -NH- or -CONH-, or an aromatic 4-, 5- or 6-membered grouping of carbon atoms, and at least one carbon atom is optionally replaced with a heteroatom selected from oxygen, sulfur, nitrogen, silicon or selenium;    D'=electron donating group selected from group of formulae (i)-(vii);    R2-R9=H, hydroxyl, methyl, ethyl, propyl, isopropyl, 4-20C alkyl, -OCH3, -OCH2CH3, -OCH2CH2CH3, -OCH(CH3)2, -OCH2CH2CH2CH3, -OCH(CH3)3, -OCH2CH2OCH3, -Cl, -Br, -I, -NH2, -NHCH3, -N(CH3)2, -N(Ph)2, -O(=O)-CH3, -O-C-(O)-CH2-CH3, substituted cyclohexyl-amine, substituted phenylamine, -O-N=C(CH3)-CH2-CH3, -Ph(R22)(R23)(R24), or group of formula (viii) or (ix);    Ph=phenyl;    R22-R27=H or -R17-Y3R17=R15;    Y3=Y1.    An INDEPENDENT CLAIM is included for photoelectric conversion device comprising at least a passive substrate having deposited on it, a conductive layer, a light-absorbing layer having the dye (I) deposited on it, an intermediate layer, and counter-electrode, where the conductive layer, light-absorbing layer, dye (I), intermediate layer, and counter-electrode are connected in series.