Synthesis and Characterization of N-(2-Ethylhexyl)carbazole-2,3-Bis(4-fluorophenyl))thieno[3,4-b]pyrazine Copolymer

摘要

The discovery of bulk heterqjunction solar cells has stimulated research in low band-gap it-conjugated polymers. The low band-gap polymers absorb a large part of the solar spectrum, and these p-type polymers (electron donors) can be used in the fabrication of photovolatic devices in combination with [6,6]-phenyl-C_(61)-butyric acid methyl ester (PCBM) as an n-type material (electron acceptor). Poly(3-hexylthiophene) (P3HT), with an optical band-gap (E_g) of ～ 2.0 eV, has been most frequently used along with PCBM in fabrication of polymer-based solar cells with power conversion efficiencies up to ～5%. However, conjugated polymers with lower E_gs than that of P3HT can lead to more enhanced absorption of sunlight, potentially increasing the photocurrent. The most common strategy to synthesize a low band-gap polymer involves incorporation of electron-rich units (donors) and electron-deficient units (acceptors) in an alternating fashion in the polymer chain.