NOVELTY - Polymer comprising one or more 1,2,5,6-tetrahydro-(1,5)naphthyridine moiety (I), is new.    USE - (I) is useful as charge transport, semiconducting, electrically conducting, photoconducting or light emitting material in an optical, electro-optical, electronic, electroluminescent or photoluminescent device, in a component of a device or in an assembly of a device or component, where the device: is organic field effect transistors (OFET), a bulk heterojunction (BHJ) organic photovoltaic device, inverted BHJ OPV device, organic photodetectors (all preferred), thin film transistors, organic LED, organic light emitting transistors (OLET), organic solar cells, laser diodes, Schottky diodes, photoconductors and photodetectors; the component is charge injection layers, charge transport layers, interlayers, planarizing layers, antistatic films, polymer electrolyte membranes (PEM), conducting substrates and conducting patterns; and the assembly is integrated circuits (IC), radio frequency identification (RFID) tags or security markings or security devices containing them, flat panel displays or their backlights, electrophotographic devices, electrophotographic recording devices, organic memory devices, sensor devices, biosensors and biochips (all claimed).    ADVANTAGE - (I) can be easily and economically prepared with high production yield, good structural organization and film-forming properties, improved charge carrier mobility and good processability, solubility in organic solvents and stability, and improves uniformity, integrity, oxidative stability, lifetime and power conversion efficiency of the electronic devices. The organic semiconductors have low bandgap thus improving cell efficiency.    DETAILED DESCRIPTION - Polymer comprising one or more 1,2,5,6-tetrahydro-(1,5)naphthyridine moiety of formula (I), is new.    X1, X2 = O or S;    R1, R2 = H, straight-chain, branched or cyclic 1-30C-alkyl, in which one or more CH2 groups are optionally replaced by -O-, -S-, -C(O)-, -C(S)-, -C(O)-O-, -O-C(O)-, -NR0-, -SiR0R00-, -CF2-, -CHR0=CR00-, -CY1=CY2- or -C=C- in such a manner that O or S atoms are not linked directly to one another and in which one or more H atoms are optionally replaced by F, Cl, Br, I or CN, aryl, heteroaryl, aryloxy or heteroaryloxy with 4-20 ring atoms which is optionally substituted by halo or one or more of the alkyl or cyclic alkyl;    Y1, Y2 = H, F, Cl or CN; and    R0, R00 = optionally substituted 1-40C-carbyl, hydrocarbyl or H, preferably H or 1-12C-alkyl.    INDEPENDENT CLAIMS are included for:    (1) a mixture or polymer blend comprising (I) and one or more polymers having semiconducting, charge transport, hole/electron transport, hole/electron blocking, electrically conducting, photoconducting or light emitting properties;    (2) a formulation comprising one or more polymers, mixtures or polymer blends, and one or more solvents, preferably organic solvents;    (3) a monomer of formula (R7-(Ar1)a-U1-(Ar2)c-R8) (VIa) or (R7-U1-(Ar1)a-U1-R8) (VIb); and    (4) the preparation of a polymer.    U1 = a unit of (I);    Ar1, Ar2 = aryl or heteroaryl that is different from U1, has 5-30 ring atoms and is optionally substituted by one or more Rs;    Rs = F, Br, Cl, -CN, -NC, -NCO, -NCS, -OCN, -SCN, -C(O)NR0R00, -C(O)X0, -C(O)R0, -NH2, -NR0R00, -SH, -SR0, -SO3H, -SO2R0, -OH, -NO2, -CF3, -SF5, optionally substituted silyl, carbyl or hydrocarbyl with 1-40C atoms that is optionally substituted and optionally comprises one or more hetero atoms; R7, R8 = Cl, Br, I, O-tosylate, O-triflate, O-mesylate, O-nonaflate, -SiMe2F, -SiMeF2, -O-SO2Z1, -B(OZ2)2, -CZ3=C(Z3)2, -C=CH, -C=CSi(Z1)3, -ZnX0 or -Sn(Z4)3;    X0 = halo, preferably Cl, Br or I; and    Z1-Z4 = alkyl or aryl (all optionally substituted), where two groups Z2 together form a cyclic group.