NOVELTY - A copolymer comprising thiophene and pyrrole diketone is new.    USE - Copolymer comprising thiophene and pyrrole diketone for organic solar battery device, organic FET and organic electroluminescent device (all claimed).    ADVANTAGE - The copolymer comprising thiophene and pyrrole diketone has high solubility, high stability, molecular weight, strong donoracceptor structure, and improves photoelectric conversion efficiency.    DETAILED DESCRIPTION - A copolymer comprising thiophene and pyrrole diketone of formula (I) is new.    R1, R2, R3=1-20C alkyl groups;and    n=1-200.    INDEPENDENT CLAIMS are also included for the following:    (1) a method for preparing copolymer comprising thiophene and pyrrole diketone, which involves reacting 2,7-bis (4,4,5,5-dimethyl-1,3,2 - two miscellaneous oxygen amyl boron alkyl) 9, 9 - dialkyl fluorene of formula (B1) and 5-alkyl thiophene (3,4-c)-pyrrole -4,6- dibromo product of formula (B2) in an oxygen free environment under presence of catalyst, alkali solution and primary organic solvent at 65-120 degrees C. Suzuki reaction is performed at 24-72 degrees C to obtain fluorene-containing thiophene and pyrrole diketone copolymer solution of formula (I). The copolymer solution of formula (I) is added into methanol, processed, deposited and suction-filtered, washed and dried to obtain toluene solution containing impurity copolymer colloid. The toluene solution is dissolved by toluene to obtain copolymer of the toluene solution. The copolymer of the toluene solution is dissolved into aqueous solution of diethyl sodium dithiocarbamate at 80-100 degrees C, and stirred and mixed. The mixed liquid is added by aluminum oxide column chromatography to separate our polymer. The polymer is leached and decompressed to remove organic solvent. Copolymer of formula (I) is extracted by an acetone Soxhlet extractor    (2) an organic solar battery device, comprising an conductive layer coated on one surface of a substrate base material as an anode and coated on a poly (3 4-ethylenedioxy thiophene): poly (styrene sulfonic acid) layer. An active layer is coated on (3, 4), poly (styrene sulfonic acid) surface of an insulating layer. The insulating layer is arranged between the active layer and one surface of a metallic aluminum layer as cathode, where the active layer comprises electron donor material and electron acceptor material, the electron acceptor material is (6, 6) -C61-butyrate, where electron donor material is pyrrole diketone unit, fluorene-containing thiophene or pyridine, the fluorene copolymer has a structural formula (I).    (3) an organic electroluminescent device, comprising conductive layer deposited on a primary surface of a substrate, as an anode. A light emitting layer is coated on the conductive layer and is arranged on a lithium-fluoride buffer layer. A metal aluminum layer is arranged on the lithium-fluoride buffer layer as a cathode, and where the light emitting layer is made of fluorene-containing thiophene and pyrrole diketone copolymer, the fluorene copolymer has a structural formula (I).    (4) an organic FET, comprising a doped silicon chip, a silicon oxide insulating layer, for modifying silicon aluminum of an alkyl chlorosilane layer coated on an acid alkyl chlorosilane organic semiconductor layer. A source electrode and a drain electrode are set on the organic semiconductor layer, where the organic semiconductor layer is made of fluorene-containing thiophene and pyrrole diketone copolymer, the fluorene copolymer has a structural formula (I).