Over 15% Efficiency in Ternary Organic Solar Cells by Enhanced Charge Transport and Reduced Energy Loss

Abstract

In this study, an efficient ternary bulk-heterojunction (BHJ) organic solar cell (OSC) is demonstrated by incorporating two acceptors, PC61BM and ITC6-4F with a polymer donor (PM6). It reveals that the addition of PC61BM not only enhances the electron mobility of the derived BHJ blend but also facilitates the exciton dissociation, resulting in a more balanced charge transport alongside with reduced trap-assisted charge recombination. Consequently, as compared to the pristine PM6:ITC6-4F device, the optimal ternary OSC is revealed to deliver an improved power conversion efficiency (PCE) of 15.11% with boosted JSC, VOC and FF simultaneously. The resultant VOC and FF are among the highest values recorded in the literature for the ternary OSCs with PCE exceeding 15%. This result thus suggests that besides improving the charge transport characteristics in devices, incorporating fullerene derivative as part of the acceptor can also improve the resultant VOC, which can reduce the energy loss to realize efficient organic photovoltaic.