NOVELTY - Boron-dipyrromethene derivative (I) is new.    USE - (I) is useful as electron donors for preparing a bulk heterojunction in a photovoltaic cell and as an organic semiconductor material for elaborating a transistor with an ambipolar field effect (all claimed).    ADVANTAGE - (I) can be easily prepared with high quantity, good solubility and filmability and very strong absorption in visible of 450-950 nm, ensures efficient transfer of electrons from the donor to the electron acceptor so as to manufacture an active layer of the photovoltaic cell with good chemical, electrical and high photochemical stabilities.    DETAILED DESCRIPTION - Boron-dipyrromethene derivative of formula (I) is new.    A = phenyl substituted by W1 (consisting of H, linear or branched 2-20 carbon chain containing heteroatoms (S, O or N), formyl, carboxyl, thiophene, thiophene-bis or ter-thiophene) or substituted by linear or branched 2-20 carbon chain containing heteroatoms (S, O, Si or N), where W1 groups are in position 3, 4 and/or 5 of phenyl, aryl that contains heteroatoms (S, O, Si or N) and is substituted by halo or linear or branched 2-20 carbon chain containing heteroatoms (S, O or N), H or 1-6C-alkyl; either    R1, R2, R1a, R2a = H, halo, 1-6C-alkyl; or    R1+R2, R1a+R2a = optionally saturated, carbon ring having 5 or 6 atoms optionally substituted by heteroatoms consisting of S, Si, O, N or P;    E1, E2 = F or -CC-L;    L = bond, 1-10C-alkenylene, saturated, linear or branched carbon chain having 1-20 carbon atoms interrupted by 1-10 oxygen atoms and L is terminated by 1-4C alkyl, phosphate or a silyl group, substituted or unsubstituted polyaomatic system which may have heteroatoms such as O, S, N such as thiophene, polythiophene, pyrene, perylene, arylene, truxene or triazatruxene;    J1 = monovalent group of formula (II);    Z = link ensuring liaison with (I) and consisting of vinyl function, acetylene function or C-C bond directly connected with (I);    X = N, O, Si or S; either    D1 = arylene, heteroarylene, benzothiadiazole or linear or branched carbon chain with 2-20 carbon atoms; or    G1, G2 = linear or branched carbon chain with 2-20 carbon atoms containing heteroatoms (S, O, Si or N); or    G1+G2+C, G2+D1+C = fused ring such as thienothiophenes or thienopyrroles; and    J2 = methyl or (II).    . INDEPENDENT CLAIMS are included for:    (1) a photovoltaic cell comprising at least one support, an anode, an active layer (heterojunction) comprising at least one electron donor and one electron acceptor and a cathode; and    (2) a transistor with an ambipolar field effect comprising a source, a drain, a grid, and a channel that comprises an organic semiconductor and is present in contact with insulated or oxide of grid.