NOVELTY - Organic solar cell comprises at least one photoactive region comprising an organic donor material in contact with an organic acceptor material and forming a donor-acceptor hetero-junction, where the photoactive region comprises phthalocyanine compounds (I).    USE - Used as organic solar cell.    ADVANTAGE - The organic solar cell has: improved efficiency due to large donor-acceptor interface area and continuous carrier conducting pathways to the opposing electrodes; and enhanced light intensity.    DETAILED DESCRIPTION - Organic solar cell comprises at least one photoactive region comprising an organic donor material in contact with an organic acceptor material and forming a donor-acceptor hetero-junction, where the photoactive region comprises phthalocyanine compounds (I) of formulae (Ia) and/or (Ib).    M = divalent metal, divalent metal atom containing group or a divalent metalloid group;    A = fused arene ring comprising benzene ring, naphthalene ring, anthracene ring or phenanthrene ring;    R1 = aryl, aryloxy, arylthio, monoarylamino, diarylamino, heteroaryl, heteroaryloxy, oligo(hetero)aryl or oligo(hetero)aryloxy (all optionally substituted with at least one substituent of R1a;    R1a = CN, OH, NO2, carboxy, halo, (halo)alkyl, (halo)cycloalkyl, (halo)alkoxy, (halo)alkylsulfanyl, amino, monoalkylamino, dialkylamino, NH(aryl) or N(aryl)2;    R2 = CN, OH, NO2, carboxy, carboxylate, SO3H, sulfonate, halo, (halo)alkyl, (halo)cycloalkyl, (halo)alkoxy, (halo)alkylsulfanyl, NH2, monoalkylamino or dialkylamino;    m = 1-16; and    n = 0-23.    An INDEPENDENT CLAIM is also included for the preparation of (Ib), where R2 is F, comprises: providing an educt composition comprising at least one substituted but-2-enedinitrile compounds of formulae (IIa)-(IId); and reacting the educt composition at an elevated temperature with a compound of a metal M.    m1, m2 = 1-4;    n1 = 1-7; and    n3 = 0-8.    Provided that: the sum of all indices m1 plus the sum of all indices m2 is not more than 15; the sum of all indices n1 plus the sum of all indices n2 is not more than 23; and the educt composition comprises at least one (IIa) or the educt composition comprises at least one (IIb) and at least one (IIc).    DESCRIPTION OF DRAWING(S) - The figure shows the solar cell with normal structure.    Transparent conducting layer (11)    Hole transport layer (12)    Layer comprising donor material (13)    Layer comprising acceptor material (14)    Metal electrode (16)