新型基于二氟苯并噻二唑和双噻吩丙烯腈共轭聚合物的设计、合成及光伏性能

摘要

设计并合成了两种基于5,6-二氟苯并噻二唑和双噻吩丙烯腈单元的D-A型共轭聚合物,聚[(5,6-二氟-苯[c][1,2,5]噻二唑-4,7-基)-交替-((E)-2,3-双(3'-(2-辛基十二烷基)-(2,2＇-双噻吩)-5,5'-基)丙烯腈)](DFBT812)和聚[(5,6-二氟-苯[c][1,2,5]噻二唑-4,7-基)-交替-((E)-2,3-双(3'-(2-癸基十四烷基)-(2,2'-双噻吩)-5,5＇-基)丙烯腈)](DFBT1014)作为聚合物太阳电池的给体材料.通过侧链工程,引入了2-辛基十二烷基和2-癸基十四烷基侧链实现对聚合物的溶解性,结晶性以及共混膜形貌的调节.研究结果表明,共轭聚合物DFBT812与PC61BM的共混膜表现出更好的相分离尺度,能够促进载流子的传输和抽取.基于共轭聚合物DFBT812的太阳电池器件取得了0.87 V的开路电压和6.25％的能量转换效率.除此之外,基于DFBT812的聚合物太阳电池器件在活性层厚度为220 nm时仍然表现出6％的能量转换效率.%In this study,two novel difluorobenzothiadiazole (DFBT)-based polymeric donors,poly[(5,6-difluoro-benzo[c][1,2,5]thiadiazol-4,7-yl)-alt-((E)-2,3-bis(3＇-(2-octyldodecyl)-(2,2＇-bithiophen)-5,5＇ -yl) acrylonitrile)] (DFBT812) and poly[(5,6-difluoro-benzo[c][1,2,5]thiadiazol-4,7-yl)-alt-((E)-2,3-bis(3＇-(2-decyltetradecyl)-(2,2＇-bithiophen)-5,5＇-yl) acrylonitdle)] (DFBT1014),possessing 2-octyldodecyl and 2-decyltetradecyl side chains,respectively,were designed,synthesized,and applied for polymer solar cells.Alkyl chains of 2-octyldodecyl and 2-decyltetradecyl were incorporated into the polymer to tune the solubility and crystallization of the polymers and morphology of the blend films.Morphological study showed that the blend film of DFBT812 with PC61BM presented much better phase separation domain,which is beneficial for charge transport and collection of charge carders in the blend film.Photovoltaic devices based on DFBT812 exhibited a power conversion efficiency (PCE) of 6.25％,outperforming those based on DFBT1014.Moreover,DFBT812-based photovoltaic devices exhibited a PCE over 6％ even when the thickness of the active layer was 220 nm.