A series of new acceptor-donor-acceptor (A-D-A) type conjugated small-molecule-dyes based on indacenodithieno[3,2-b]thiophene (IDTT) and 2-(2-methyl-4H-chromen-4-ylidene)malononitrile (CMCN), named IDTT-CMCN and IDTT-HT-CMCN, have been synthesized for application in organic solar cells. A-D-A type small-molecules with CMCN can effectively form a powerful push-pull structure that induces effective intramolecular charge transport (ICT) and enhanced optical absorption. In comparison with IDTT-CMCN, IDTT-HT-CMCN has 3-hexylthiophene (HT) as a π-bridge unit between the IDTT and CMCN moieties to increase the solubility and extend the π-conjugation length. The resulting dye (IDTT-HT-CMCN) with a hexylthiophene ring as a π-bridge showed a smaller band gap and better solubility. Thus, a power conversion efficiency (PCE) as high as 7.60% was achieved with a short circuit current of 12.7 mA/cm², open circuit voltage of 0.94 V, and fill factor of 63.8%. To the best of our knowledge, small-molecule-based donors with CMCN as an electron-withdrawing unit have never been reported before. In addition, the PCE of 7.60% reported in this work is highly efficient among the PCE reported for an organic solar cell using an IDTT-based small-molecule-donor material.

一系列新的受体-供体-受体（ADA）型的共轭基于indacenodithieno小分子染料并[3,2- b ]噻吩（IDTT）和2-（2-甲基-4- ħ -苯并吡喃-4-亚基）已经合成了丙二腈（CMCN），分别称为IDTT-CMCN和IDTT-HT-CMCN，以用于有机太阳能电池。具有CMCN的ADA型小分子可以有效地形成强大的推挽结构，从而诱导有效的分子内电荷传输（ICT）和增强的光吸收。与IDTT-CMCN相比，IDTT-HT-CMCN具有3-己基噻吩（HT）作为两基团之间的π桥单元。IDTT和CMCN部分可增加溶解度并延长π共轭长度。具有己基噻吩环作为π桥的所得染料（IDTT-HT-CMCN）显示出较小的带隙和较好的溶解性。因此，在12.7mA / cm ^2的短路电流，0.94V的开路电压和63.8％的填充系数的情况下，实现了高达7.60％的功率转换效率（PCE）。据我们所知，以前从未报道过以CMCN作为吸电子单元的小分子供体。另外，在这项工作中报道的7.60％的PCE在报道的使用IDTT基小分子供体材料的有机太阳能电池的PCE中非常高效。