NOVELTY - A fluorene derivative is obtained by reacting 1,3-bis-(dihalo-phenyl)-cyclopenta(a)indene-2,8-dione or 1,3-diphenyl-cyclopenta(a)indene-2,8-dione with 2,5-norbornadiene, obtaining 1,4-bis-(4-bromo-phenyl)-fluoren-9-one (I), and reacting 1,3-bis-(dihalo-phenyl)-cyclopenta(a)indene-2,8-dione or 1,3-diphenyl-cyclopenta(a)indene-2,8-dione with N-phenyl maleimide, obtaining 4,10-bis-(4-bromo-phenyl)-2-phenyl-indeno(1,2-f)isoindole-1,3,9-trione (II), reacting compound (I) and compound (II) with thiophene-boronic acid.    USE - Fluorene derivative is used for organic electroluminescent material and solar cell.    ADVANTAGE - The fluorene derivative has excellent heat stability.    DETAILED DESCRIPTION - An INDEPENDENT CLAIM is included for preparation of fluorene derivative, which involves dropping chloroacetic acid in dichloromethane to N,N'-dicyclohexylcarbodiimide and dimethylaminopyridine in dichloromethane, obtaining 1,3-bis(4-halo-phenyl)-2-propanone or 1,3-bis(2-halo-phenyl)-2-propanone, reacting, adding 10% methanol or potassium hydroxide and ninhydrin to 1,3-bis(4-halo-phenyl)-2-propanone or 1,3-bis(2-halo-phenyl)-2-propanone, reacting to obtain 1,3-bis (4-bromophenyl)-indeno(a)pentalene-2,8-dione and 1,3-(2-bromophenyl)- indeno(a)pentalene-2,8-dione, mixing norbornadiene in toluene with obtained mixture, refluxing, obtaining 9- oxo-1,4-bis(4-bromophenyl) fluorene, 9-oxo-1,4-bis (2-bromophenyl)fluorene, or 9-oxo-1,4-diphenylfluorenyl, adding maleamic acid anhydride in aniline, adding sodium acetate, obtaining N-phenyl maleimide, mixing 9-oxo-1,4-bis(4-bromophenyl) fluorene, 2-thiophene boronic acid, and tetrakis(triphenylphosphine) palladium, reacting under nitrogen atmosphere, adding sodium carbonate, obtaining 9-oxo-1,4-bis(4-(thienyl) phenyl) fluorene, and adding tetrahydrofuran to obtained mixture. The ratio of chloroacetic acid to N,N'-dicyclohexylcarbodiimide is 1:0.5-0.95. The ratio of N,N'-dicyclohexylcarbodiimide to dimethylaminopyridine is 4:1-2. The ratio of chloroacetic acid to dichloromethane is 1:20-100. The ratio of potassium hydroxide to 1,3-bis(4-halo-phenyl)-2-propanone or 1,3-bis(2-halo-phenyl)-2-propanone is 1-2.5:1:2-3:1.3. The ratio of 1,3-bis(4-halo-phenyl)-2-propanone and 1,3-bis(2-halo-phenyl)-2-propanone to ethanol is 1:30-100. The ratio of 9-oxo-1,4-bis(4-bromophenyl) fluorene to norbornadiene is 1:1-5. The molar ratio of 9-oxo-1,4-bis(4-bromophenyl) fluorene to toluene is 1:60-100.