Linear Side Chains in Benzo[1,2-b:4,5-b′]dithiophene-Thieno[3,4-c]pyrrole-4,6-dione Polymers Direct Self-Assembly and Solar Cell Performance
Linear Side Chains in Benzo[1,2-b:4,5-b′]dithiophene-Thieno[3,4-c]pyrrole-4,6-dione Polymers Direct Self-Assembly and Solar Cell Performance
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DOI：
10.1021/ja400365b
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发表时间：
2013-03-27
影响因子：
15
通讯作者：
Beaujuge, Pierre M.
中科院分区：
文献类型：
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作者：
Cabanetos, Clement;El Labban, Abdulrahman;Beaujuge, Pierre M.
虽然g-共轭聚合物中增溶侧链的大小和分支的变化会影响其在薄膜器件中的自组装性能，但这些结构变化仍然很难预测。这份报告强调了线性侧链取代基在用于体异质结太阳能电池的poly(benzo[1，2-b:4，5-b‘]dithiophene-thieno[3，4-c]pyrrole-4，6-dione)(PBDTTPD)聚合物中的决定作用。我们发现，用BDT基序中的直链取代支链会导致薄膜中聚合物自组装和主链取向的关键变化，这与太阳能电池效率的急剧下降相关。相反，我们发现对于具有支链烷基取代的BDT基序的聚合物，控制线性N-烷基取代的TPD基序中的脂肪碳的数量是改善材料性能的主要贡献。通过这种方法，PBDTTPD聚合物在采用PC71BM的BHJ器件中的功率转换效率达到8.5%，开路电压达到0.97V，使PBDTTPD成为用于串联太阳能电池高带隙电池的最佳聚合物施主之一。
While varying the size and branching of solubilizing side chains in g-conjugated polymers impacts their self-assembling properties in thin-film devices, these structural changes remain difficult to anticipate. This report emphasizes the determining role that linear side-chain substituents play in poly(benzo[1,2-b:4,5-b']dithiophene-thieno[3,4-c]pyrrole-4,6-dione) (PBDTTPD) polymers for bulk heterojunction (BHJ) solar cell applications. We show that replacing branched side chains by linear ones in the BDT motifs induces a critical change in polymer self-assembly and backbone orientation in thin films that correlates with a dramatic drop in solar cell efficiency. In contrast, we show that for polymers with branched alkyl-substituted BDT motifs, controlling the number of aliphatic carbons in the linear N-alkyl-substituted TPD motifs is a major contributor to improved material performance. With this approach, PBDTTPD polymers were found to reach power conversion efficiencies of 8.5% and open-circuit voltages of 0.97 V in BHJ devices with PC71BM, making PBDTTPD one of the best polymer donors for use in the high-band-gap cell of tandem solar cells.