NOVELTY - Substituted pyrene compounds (I) are new.    USE - (I) are useful in a transistor and an organic semiconductor device (claimed), preferably LCD, organic LED, a plasma display panel, a surface-conduction electron-emitter display, solar cell, memory device, photosensor and laser device.    ADVANTAGE - (I) exhibit excellent charge mobility, oxidation stability and electrical reliability. (I) provides: organic semiconductor device with light weight and transistor with good uniformity and high electrical characteristics (in a doping state) and good insulating characteristics (in a non-doping state).    DETAILED DESCRIPTION - Substituted pyrene compounds of formula (I) are new.    X1-X4 = S, N or CR50, where at least one of X1-X4 is S;    R50 = linear 1-20C-alkyl, branched 1-20C-alkyl, 6-20C-aryl (all optionally substituted), or H;    R1-R8 = linear 1-20C-alkyl group, branched 1-20C-alkyl, 3-20C-cycloalkyl, 1-20C-alkoxy, 3-20C-cycloalkyloxy, 6-30C-aryl, 6-30C-aryloxy, 2-30C-heteroaryl, 2-30C-heteroaryl ring group including at least one electron withdrawing imine nitrogen atom, 2-30C-heteroaryl ring group including at least one S, NR51R52, C(O)OR53 and/or C(O)NR54R55, H or halo, where two adjacent substituents of R1-R6 are linked to each other to provide a thiophenyl ring group fused with a pyrene moiety and a thiazolyl ring group fused with a pyrene moiety (all optionally substituted), R7 and R8 contain above groups, when at least one of X1-X4 is S, and the other one of X1-X4 is CR50 and at least one of R1-R6 is one of 2-30 heteroaryl ring group including at least one electron withdrawing imine nitrogen atom; and    R51-R55 = linear 1-20C-alkyl group, branched 1-20C-alkyl, 3-20C-cycloalkyl, 6-30C-aryl, 2-30C-heteroaryl (all optionally substituted) or H.    INDEPENDENT CLAIMS are included for:    (1) a transistor (10) comprising (I) or an organic semiconductor polymer; and    (2) an organic semiconductor polymer comprising a pyrene structural unit of formula (V).    Ar1, Ar2 = 6-30C-aryl, 4-14C heteroaryl, 6-30C-condensed polycyclic group (all optionally substituted), preferably phenylene, thiophene, benzothiophene, thienothiophene, thiazole, thiazolothiazole, fluorene or carbazole (all optionally substituted); and    p, q = 0-10, provided that when p or q are each greater than or equal to 2, many of Ar1 and Ar2 are the same or different from each other.    DESCRIPTION OF DRAWING(S) - The figure shows a schematic cross-sectional view of a transistor.    Transistor (10)    Substrate (12)    Gate electrode (14)    Insulation layer (16)    Source electrode (17a)    Drain electrode (17b)    Active layer. (18)