17.2% efficiency for completely non-fused acceptor organic solar cells via re-intermixing strategy in D/A stratified active layer

Abstract

Pursuing power conversion efficiency (PCE) is the priority of developing organic solar cells (OSCs) based on low-cost completely non-fused ring acceptors. Herein, a donor/acceptor re-intermixing strategy to enhance the photon capturing process, based on a previously established well-stratified active layer morphology is reported. By adding 20 wt% PTQ10 (polymer donor) into the acceptor's precursor, the device PCE is increased to 16.03% from 15.11% of the D18/A4T-16 control system, which is attributed to the additional charge generation interface and suppressed bimolecular recombination. On the contrary, using the equal ratio of PM6 leads to significant efficiency loss, indicating the importance of considering vertical distribution from the perspective of thermodynamics. Moreover, a cutting-edge level of 17.21% efficiency for completely non-fused ring acceptor systems is realized by altering the active layer to PBQx-TF/TBT-26 and PTQ11, via the identical processing strategy. This work thus presents attractive device engineering and solar cell performance, as well as in-depth vertical morphology understanding.