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

Despite the significant progress made recently in all-polymer solar cells (all-PSCs), it is still quite challenging to achieve high open-circuit voltage (V-oc) and short-circuit current density (J(sc)) 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 J(sc)s of the resulting all-PSCs. However, such modifications have also depressed V-oc, 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 J(sc) (24.1 mA cm(-2)) and V-oc (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 V-oc and J(sc) to achieve high-efficiency all-PSCs.

Automated summary

A novel polymer acceptor, PYT-1S1Se, designed with an asymmetrical selenophene-fused framework, has been shown to optimize optical absorption and electronic properties in all-polymer solar cells. Compared with other analogs, all-PSCs derived from PYT-1S1Se demonstrate improved J(sc) and V-oc metrics, resulting in a record-high power conversion efficiency of 16.3%.