Four thieno[3,2-b]thiophene (TT)-based donor-π-acceptor–type small-molecule donors DTCPTT, DTCPTT-2CN, DTDCPTT, and DTDCPTT-2CN were synthesized and characterized. A clear structure-property relationship correlating the effects of introducing cyano groups onto the TT and the end-capping groups has been successfully established. DTDCPTT and DTDCPTT-2CN were adopted as electron donors for organic photovoltaics (OPVs) mainly due to the strong intramolecular charge transfer absorption in the visible light region, sufficiently high thermal stability, and appropriate energy level alignment with C₇₀. Moreover, the analyses of crystal structures reveal that DTDCPTT and DTDCPTT-2CN form antiparallel dimer pairs through strong dipolar and non-covalent intermolecular interactions. X-ray structures also indicate that introducing cyano groups onto the TT moiety does not affect the backbone planarity significantly. Compared with DTDCPTT-2CN, the more compact and uniform crystal packing renders DTDCPTT advantageous for exciton dissociation and charge carrier transport. DTDCPTT-based device achieves power conversion efficiency as high as 7.81% and 16.89%, respectively, under simulated AM 1.5G illumination and 500 lux TLD-840 fluorescent lamp illumination, which could be attributed to stronger absorption and better photocurrent extraction. In addition, both devices exhibit high stability under continuous simulated 1 sun illumination for more than 300 h. As far as we know, this is the best performance for vacuum-processed small-molecule indoor OPVs to date.

合成并表征了四种基于噻吩并[3,2- b ]噻吩（TT）的供体-π-受体型小分子供体DTCPTT，DTCPTT-2CN，DTDCPTT和DTDCPTT-2CN。已经成功地建立了清晰的结构-性质关系，该关系与将氰基基团引入TT和封端基团的效果相关。DTDCPTT和DTDCPTT-2CN被用作有机光伏（OPV）的电子给体，主要是因为在可见光区域内分子内的电荷转移吸收能力强，热稳定性足够高，并且能级与C _{70保持一致}。此外，晶体结构分析表明，DTDCPTT和DTDCPTT-2CN通过强的偶极和非共价分子间相互作用形成反平行二聚体对。X射线结构还表明将氰基基团引入TT部分不会显着影响主链平面性。与DTDCPTT-2CN相比，更紧凑，更均匀的晶体堆积使DTDCPTT在激子离解和电荷载流子传输方面具有优势。基于DTDCPTT的设备在模拟AM 1.5G照明和500 lux TLD-840荧光灯照明下分别实现了高达7.81％和16.89％的功率转换效率，这可以归因于更强的吸收能力和更好的光电流提取能力。此外，在连续模拟的1个阳光照射下超过300小时，这两种设备都具有很高的稳定性。据我们所知，这是迄今为止真空处理的小分子室内OPV的最佳性能。