Non-halogen solvent processed all-polymer organic solar cells with improved vertical phase morphology

Abstract

All-polymer organic solar cells (PSCs) have attracted much attention owing to their outstanding mechanical stress strength, high stability and promising potential for flexible synthesis. However, it is difficult to form an ideal vertical morphology for traditional bulk heterojunction (BHJ) PSCs, limiting the further improvement in their device efficiency. In this study, we fabricated bilayer devices based on a PM1/PYF-T-o system for the first time using a sequential coating method instead of the one-step spin-coating method to optimize the vertical phase distribution. Notably, when the non-halogen solvent (o-xylene) was applied to prepare the active layer, the green bilayer devices obtained a PCE of 16.32%, which was better than that of BHJ devices (15.83%). Hence, the third component PBDB-TF was exclusively introduced into PM1 to directionally regulate the morphology of the donor layer, enhance the film crystallization, and further improve the charge transport and collection process. Consequently, the PM1:PBDB-TF/PYF-T-o-based bilayer devices achieved an excellent PCE of 17.66%, which is one of the highest efficiencies achieved for non-halogen bilayer PSCs. Moreover, the devices maintained an 83.75% of their original efficiency after 800 hours of storage. This work provides a novel idea for the development of high-performance all-polymer devices, which are conducive to future commercial applications.