The invention discloses a benzodithiophene
polymer, its preparation method, a
semiconductor composition containing it, and a
solar cell using it. The benzodithiophene
polymer has a structure represented by a formula shown in the specification; and in the formula, A1, A2, A3, B1, B2 and B3 are respectively independently selected from
hydrogen, C1-C30
alkyl groups, C1-C30 alkyloxy groups, cyan groups, nitro groups, ester groups,
aryl groups with four following
substituent groups RX, heteroaryl groups with four following
substituent groups RX, aralkyl groups with four following
substituent groups RX,
halogen atoms, halogenated
alkyl groups, heteroalkyl groups, alkenyl groups and alkynyl groups; the substituent groups RX comprise
hydrogen, C1-C30
alkyl groups, C1-C30 alkyloxy groups, ester groups,
sulfonyl groups or fluorinated alkyl groups. The introduction of a
thiophene side chain to benzodithiophene makes the obtained
polymer molecule have a high conjugate degree, so it is in favor of improving the carrier mobility of the above polymer material.