Tailoring End-Group π-Conjugation in Nonfullerene Acceptors for Enhanced Photovoltaic and Photocatalytic Hydrogen...

The development of Y-series nonfullerene acceptors (NFAs) has significantly advanced the power conversion efficiency (PCE) of organic solar cells, surpassing 20%, while also demonstrating promising performance in bulk-heterojunction photocatalysis. Extending the π-conjugation of end groups is an effective strategy to tune molecular energy levels, enhance optical absorption, and optimize intermolecular packing, yet the effects on both photovoltaic and photocatalytic performance remains insufficiently explored. NFAs featuring an indanone-based central core have demonstrated excellent photovoltaic and photocatalytic performance. In this study, we design two novel NFAs, NQF-F and NQF-FN, derived from a common indanone-based NQF backbone, incorporating phenyl- and naphthyl-fuzed indanone end groups. The extended π-conjugation in NQF-FN results in broader absorption, improved charge transport, and a higher PCE of 17.06%, outperforming NQF-F (16.29%). More importantly, PM6:NQF-FN-based photocatalysts achieve a hydrogen evolution rate of 217.5 mmol h^-1 g^-1 with only 10 wt% Pt, compared to 214.4 mmol h^-1 g^-1 for PM6:NQF-F, despite a fourfold reduction in Pt content. These findings underscore the potential of end-group conjugation extension to enhance both photovoltaic and photocatalytic performance while reducing reliance on precious metals, providing critical design insights for multifunctional NFAs in energy conversion applications.