16.3% Efficiency binary all-polymer solar cells enabled by a novel polymer acceptor with an asymmetrical selenophene-fused backbone

Abstract

Despite the significant progress made recently in all-polymer solar cells (all-PSCs), it is still quite challenging to achieve high open-circuit voltage (Voc) and short-circuit current density (Jsc) simultaneously in order to further improve their performance. The recent strategy of using selenophene to replace thiophene on the Y6 based polymer acceptors has resulted in significantly improved Jscs of the resulting all-PSCs. However, such modifications have also depressed Voc, which compromises the overall performance of the devices. Herein, we present the design and synthesis of a novel polymer acceptor, PYT-1S1Se, created by inserting an asymmetrical selenophene-fused framework to precisely manipulate optical absorption and electronic properties. Compared with the selenium-free analog, PYT-2S, and symmetrical selenium-fused analog, PYT-2Se, the PYT-1S1Se derived all-PSCs not only deliver optimized Jsc (24.1 mA cm−2) and Voc (0.926 V) metrics, but also exhibit a relatively low energy loss of 0.502 eV. Consequently, these devices obtain a record-high power conversion efficiency (PCE) of 16.3% in binary all-PSCs. This work demonstrates an effective molecular design strategy for balancing the trade-off between Voc and Jsc to achieve high-efficiency all-PSCs. © 2021, Science China Press and Springer-Verlag GmbH Germany, part of Springer Nature.