Exciton engineering in organic photocatalysis: mechanisms and applications

Organic photocatalysts, with tunable structures, abundant resources, and adjustable bandgaps, serve as versatile platforms for solar energy conversion, synthesis, and environmental remediation. To date, numerous organic photocatalysts have been developed as ideal models for studying photophysical processes and excited states. However, a comprehensive understanding of exciton dynamics, intersystem crossing, and their correlation and pathway with photocatalytic activity in these organic systems remains elusive, warranting further investigation and analysis. In particular, processes involving triplet excitons, such as room-temperature phosphorescence (RTP) and thermally activated delayed fluorescence (TADF), have not been fully utilized or studied in organic photocatalysis. Here, this review is provided on the advancements in exciton mechanisms for enhancing pure organic photocatalysis, focusing on how molecular design influences exciton behavior and the contribution of excitons to photocatalytic processes and performance under different luminescence mechanisms. Unlike traditional bandgap engineering, which primarily enhances photocatalytic performance by adjusting semiconductor bandgaps and carrier generation, the “exciton regulation” highlighted in this review focuses on prolonging exciton lifetime and improving utilization efficiency. This approach enables precise control over photocatalytic reaction pathways and selectivity. Beyond the basic information, challenges and opportunities are identified, and innovative strategies for designing organic photocatalysts through exciton regulation are proposed. • Comprehensive review of excitonic photophysical mechanisms in pure organic photocatalysis. • A systematic analysis of exciton regulation mechanisms and excited states was described. • Opportunities and challenges of exciton engineering for enhancing pure organic photocatalysis are proposed.