NOVELTY - Polymer comprising a thieno(3,2-b)thiophene-2,5-dione units (I) are new.    USE - The polymer is useful as semiconducting material, which is useful in an electronic device such as organic field effect transistor, organic photovoltaic device (all claimed), organic LEDs and organic electrochromic devices.    ADVANTAGE - The organic polymeric semiconducting materials are cost-effective, and exhibit light weight and high charge carrier mobility and stability.    DETAILED DESCRIPTION - Polymer comprising a thieno(3,2-b)thiophene-2,5-dione units of formula (I) are new.    G1, G2 = 6-14C arylene, bivalent 5-14 membered aromatic heterocyclic residue (both optionally substituted with 1-6 substituents of Ra1), alkene group of formula cis- or trans (-C(R11)=C(R12)-), or (-CC-);    Ra1 = 1-30C alkyl, 2-30C alkenyl or 2-30C alkynyl (all optionally substituted with 1-6 substituents of Rc1), 3-10C cycloalkyl, 5-10C cycloalkenyl or monovalent 3-14 membered aliphatic heterocyclic residue (all optionally substituted with 1-6 substituents of Rd1), =O, =C(CN)2, -O-2-6C alkylene-O-, halo, -CN, -NO2, -OH, 1-30C alkoxy, -O-CH2CH2O-1-30C alkyl, -O-COR1, -S-1-30C alkyl, -NH2, -NHR1, -NR1R2, -NH-COR1, -COOH, -COOR1, -CONH2, -CONHR1, -CONR1R2, -CO-H or -COR1;    R1, R2 = 1-30C alkyl, 2-30C alkenyl, 2-30C alkynyl, 3-10C cycloalkyl, 5-10C cycloalkenyl, monovalent 3-14 membered aliphatic heterocyclic residue, 6-14C aryl or monovalent 5-14 membered aromatic heterocyclic residue;    Rc1 = =O, =C(CN)2, -O-2-6C alkylene-O-, halo, -CN, -NO2, -OH, 1-10C alkoxy, -O-CH2CH2O-1-10C alkyl, -O-COR3, -S-1-10C alkyl, -NH2, -NHR3, -NR3R4, -NH-COR3, -COOH, -COOR3, -CONH2, -CONHR3, -CONR3R4, -CO-H, -COR3, 3-10C cycloalkyl, monovalent 3-14 membered aliphatic heterocyclic residue, 6-14C aryl or monovalent 5-14 membered aromatic heterocyclic residue;    Rd1 = =O, =C(CN)2, -O-2-6C alkylene-O-, halo, -CN, -NO2, -OH, 1-10C alkoxy, -O-CH2CH2O-1-10C alkyl, -O-COR3, -S-1-10C alkyl, -NH2, -NHR3, -NR3R4, -NH-COR3, -COOH, -COOR3, -CONH2, -CONHR3, -CONR3R4, -CO-H, -COR3, 1-10C alkyl, 2-10C alkenyl, 2-10C alkynyl, 6-14C aryl or monovalent 5-14 membered aromatic heterocyclic residue;    R3, R4 = 1-10C alkyl, 2-10C alkenyl, 2-10C alkynyl, 3-10C cycloalkyl, 5-10C cycloalkenyl, monovalent 3-14 membered aliphatic heterocyclic residue, 6-14C aryl or monovalent 5-14 membered aromatic heterocyclic residue;    R11, R12 = H or 1-30C alkyl;    L = 6-24C arylene, bivalent 5-24 membered aromatic heterocyclic residue (both optionally substituted with 1-6 substituents of Rb1), alkene group of formula cis- or trans (-C(R11)=C(R12)-), or (-CC-);    Rb1 = 1-30C alkyl, 2-30C alkenyl or 2-30C alkynyl (all optionally substituted with 1-6 substituents of Re1), 3-10C cycloalkyl, 5-10C cycloalkenyl or monovalent 3-14 membered aliphatic heterocyclic residue (all optionally substituted with 1-6 substituents of Rf1), =O, =C(CN)2, -O-2-6C alkylene-O-, halo, -CN, -NO2, -OH, 1-30C alkoxy, -O-CH2CH2O-1-30C alkyl, -O-COR5, -S-1-30C alkyl, -NH2, -NHR5, -NR5R6, -NH-COR5, -COOH, -COOR5, -CONH2, -CONHR5, -CONR5R6, -CO-H or -COR5;    R5, R6 = 1-30C alkyl, 2-30C alkenyl, 2-30C alkynyl, 3-10C cycloalkyl, 5-10C cycloalkenyl, monovalent 3-14 membered aliphatic heterocyclic residue, 6-14C aryl or monovalent 5-14 membered aromatic heterocyclic residue;    Re1 = =O, =C(CN)2, -O-2-6C alkylene-O-, halo, -CN, -NO2, -OH, 1-10C alkoxy, -O-CH2CH2O-1-10C alkyl, -O-COR7, -S-1-10C alkyl, -NH2, -NHR7, -NR7R8, -NH-COR7, -COOH, -COOR7, -CONH2, -CONHR7, -CONR7R8, -CO-H, -COR7, 3-10C cycloalkyl, monovalent 3-14 membered aliphatic heterocyclic residue, 6-14C aryl or monovalent 5-14 membered aromatic heterocyclic residue;    Rf1 = =O, =C(CN)2, -O-2-6C alkylene-O-, halo, -CN, -NO2, -OH, 1-10C alkoxy, -O-CH2CH2O-1-10C alkyl, -O-COR7, -S-1-10C alkyl, -NH2, -NHR7, -NR7R8, -NH-COR7, -COOH, -COOR7, -CONH2, -CONHR7, -CONR7R8, -CO-H, -COR7, 1-10C alkyl, 2-10C alkenyl, 2-10C alkynyl, 6-14C aryl or monovalent 5-14 membered aromatic heterocyclic residue;    R7, R8 = 1-10C alkyl, 2-10C alkenyl, 2-10C alkynyl, 3-10C cycloalkyl, 5-10C cycloalkenyl, monovalent 3-14 membered aliphatic heterocyclic residue, 6-14C aryl or monovalent 5-14 membered aromatic heterocyclic residue;    R9, R10 = H, 1-30C alkyl, -CN or halo;    q, s = 0-5;    r = 0-2; and    n = 2-10000.