18.4% efficiency achieved by the cathode interface engineering in non-fullerene polymer solar cells

The suitable cathode interlayer (CIL) plays a vital role in improving the photovoltaic performances of polymer solar cells, and small-molecule CILs with simple structure and significant modification are believed to have a prospect for commercialization. Herein, we apply the molecular tailoring strategy and synthesize a conjugated small-molecule CIL named SME1, which shows the better reproducibility in different batches than that polymer counterpart and thus ensure the consistent modification effect. It is found that, except for optimizing the molecule/metal contact to decrease the traps, SME1 can also extract electrons from the polymer donor and establish the available n-doping with the non-fullerene acceptor, which are conducive to more efficient exciton dissociation and charge collection in varied non-fullerene systems. By applying SME1 as CIL, one of top power conversion efficiencies of 18.4% (17.9% by the third-party certification) is achieved in PM6:BTP-eC9-based device. In this sense, SME1 can indeed help the emerging photovoltaic materials realize their full potential. (c) 2021 Published by Elsevier Ltd.

Automated summary

The study demonstrates the potential of synthesized small-molecule CIL SME1 in improving the performance of polymer solar cells by optimizing exciton dissociation and charge collection, achieving a high power conversion efficiency of up to 18.4% in PM6:BTP-eC9-based devices.