Tuning photovoltaic performance of DOBT-based dyes via molecular design with ethynyl-linker and terminal electron-donating segment

A series of novel D-π-A-π-D type DOBT-based dyes named TPAEDOBT, CZEDOBT, TPADOBT and CZDOBT have been designed and synthesized successfully for solution-processable BHJ-OSCs. Their PV properties were finely tuned via the molecular design with ethynyl-linker and terminal electron-donating units. By contrast, the relatively high PCE of 3.21% has been achieved for TPAEDOBT-based device due to its triple-bond effect and high hole-mobility capacity. Most importantly, a remarkably increased Voc of 1.06 V has been obtained for CZEDOBT-based device due to the synergistic effect of ethynyl-linker with electron-withdrawing character and Cz units with the relatively weakened electron-donating ability, which is among the earliest report for DOBT-ethynyl-Cz based SMs with high Voc so far. The results provide the valuable hints for rational design of novel SMs-donor materials.251