NOVELTY - A naphthalene copolymer compound (I) comprises naphthalene tetracarboxylic acid compound (II) and diimide-dithiophene quinoxaline compound (III).    USE - Copolymer for use in an organic solar battery device, an organic electroluminescent device and an organic FET (all claimed).    ADVANTAGE - The copolymer has better dissolvability, strong absorbance and wide absorption region that extends to the near infrared region, and improves utilization rate of sunlight and better charge transport performance.    DETAILED DESCRIPTION - A naphthalene copolymer compound of formula (I) comprises naphthalene tetracarboxylic acid compound of formula (II) and diimide-dithiophene quinoxaline compound of formula (III).    n=1-100;    R1, R2=hydrogen, C 1-20 alkyl, alkoxy;and    R3, R4= C 1-20 alkyl or alkoxyl.    . INDEPENDENT CLAIMS are also included for the following:    (1) a method for preparing copolymer comprising naphthalene tetracarboxylic acid diimide-dithiophene quinoxaline, which involves mixing naphthalene tetracarboxylic acid diimide 2-bromide and 2, 9-bi-butyl-thiophene (3, 2-f, 2', 3'-h) quinoxaline derivative according to mol ratio of 1:1 to 2:1 at the temperature of 50-120 degrees C, and performing coupling reaction for 24 to 72 hours to obtain copolymer comprising naphthalene tetracarboxylic acid diimide-dithiophene quinoxaline    (2) an organic solar battery device comprising a substrate base material, a conductive layer depositing on the surface of the substrate base material as an anode, poly(3 4-ethylenedioxy thiophene) coated on the conductive layer, an active layer of poly(styrene sulfonic acid), and a metallic aluminium layer arranged on a surface of the active material as a cathode, where the active layer comprises electron donor material and electron acceptor material    (3) an organic electroluminescent device comprising a substrate, a conductive layer deposited on the surface of the substrate as an anode, a light emitting layer coated on the conductive layer, a buffer layer coated on the light emitting layer, and a metal aluminum layer arranged on the buffer layer as a cathode    (4) an organic field effect transistor comprising a doped silicon chip, an silicon dioxide insulating layer, an organic semiconductor layer coated on the acid alkyl chlorosilane layer, a source electrode and a drain electrode arranged on the organic semiconductor layer.