NOVELTY - A polymer (I), is new.    USE - New polymer is used for composition for organic-semiconductor material and coating film, and organic photoelectric conversion element for organic thin-film solar cell (all claimed) and wet dye-sensitized solar cell.    ADVANTAGE - The organic thin-film solar cell comprising organic photoelectric conversion element has excellent photoelectric conversion efficiency with low energy level.    DETAILED DESCRIPTION - A polymer of formula (I), is new.    D=group of formula (Ia);    wA1=group of formula (Ib);    A=group of formula (Ic);    wA2=group of formula (Id);    l,m3,m1+m2,o3=1 or more;    m1,m2,o1,o2,o4=0 or more;    n=2-1000;    D1=donor structural unit which consists of condensed ring;    A1-A3=acceptor property structural unit which consists of ring with hetero atom containing aromatic ring;    R1,R2,R4=H, halo, alkyl, alkenyl or alkynyl;    R3=alkyl, alkenyl or alkynyl;    L1-L4=bivalent coupling group chosen from single bond or -O-, -S-, -NR5-, -C(=O)O-, -C(=S)O-, -C(=O)S-, -SC(=O)-, -OC(=O)-, -OC(=S)-, -C(=O)-, -C(=S)-, -C(=O)NR5-, -NR5C(=O)-, -S(=O)-, -S(=O)2-, -S(=O)2O-, -OS(=O)2-, -S(=O)2NR5-, -NR5S(=O)2-, arylene and hetero arylene;and    R5=H or hydrocarbyl.    (i) The level of the lowest unoccupied molecular orbital of wA1 and wA2 is -0.21eV to -2.0eV; (ii) The level of the lowest unoccupied molecular orbital of A is lower than the level of the lowest unoccupied molecular orbital of wA1 and wA2; and (iii) D is condensed ring which has at least one thiophene ring. INDEPENDENT CLAIMS are included for the following:    (1) organic photoelectric conversion element, which comprises electrode (a), electrode (b), and photoelectric converting layer (3) positioned between electrodes (a) and (b). The photoelectric converting layer has polymer (I);    (2) organic thin-film solar cell (10);    (3) composition, which contains polymer and organic solvent;    (4) coating film, which is formed using composition; and    (5) cyclopentadiene compound of formula (M1).    X1=sulfur atom, oxygen atom, selenium atom, tellurium atom or -NR5- or -Y1=Y2-;    Y1,Y2=N or -CR6=;    R6=H or substituent;    X6,X9=S, O, Se, Te or -NR5-;    X7,X8=N or -C(-L1-R1)=, in which at least one of X7 and X8 is N;    X10,X11=N or -C(-L2-R2)=, in which at least one of X10 and X11 is N;    Z1,Z2=halo, perfluoro alkane sulfonyloxy, trialkyl tin, trialkylsilyl, or -B(OR( alpha ))2;and    R( alpha )=H, alkylsulfonyl, alkyl or aryl.    DESCRIPTION OF DRAWING(S) - The drawing shows a schematic view of the organic thin-film solar cell. (Drawing includes non-English language text)    Photoelectric converting layer (3)    Support component (7)    Organic thin-film solar cell (10)    Electrodes (11,12)    Hole transportation layer (21)