Mechanisms of Exciton Formation and Long-Lived States in Polymeric Carbon Nitrides

Polymeric carbon nitrides (PCNs) exhibit intriguing optical properties and exceptional performance in (photo)catalysis, optoelectronics, and energy storage. Nevertheless, the intricate phenomena involving light absorption extending to the visible range, long-lived excitons, photo-charging, and photochemical processes observed in PCN derivatives remain poorly understood. Our theoretical investigation elucidates the role of distinct dark and bright exciton species, exciton lifetimes, and exciton stability, correlating these findings with the microstructural attributes of PCNs. Furthermore, we elucidate the origin of trapped excitons within PCNs and deliberate on the role of trapped excitons in catalytic reactivity.