A Novel Thiophene-fused Ending Group Enabling an Excellent Small Molecule Acceptor for High-performance Fullerene-free Polymer Solar Cells with 11.8% Efficiency

摘要

In this article, we designed and synthesized a novel small molecule acceptorof ITCPTC with thiophene-fused ending group by employing a new active methyleneprecursor of CPTCN. The ITCPTC based polymer solar cells with PBT1-EH as donorachieved very high PCEs of up to 11.8% with a remarkably enhanced fill factor(FF) of 0.751, a near 20% boost in PCE with respect to the ITIC based controldevice. These values are among the highest PCEs and FFs for PSCs. In the wholestudy, we made contrasts with ITIC to understand the reasons of excellentperformance of ITCPTC-based PSCs through various measurements, such as GIWAXSand RSoXS. We revealed that the simple modification of ITIC into ITCPTC notonly change the material electronic structure, but also mediate the materialinteractions and crystallization, which contribute together to the excellentperformance of ITCPTC based PSCs.