Near-Infrared-Light Triggered Electron Transfer from Ag2S Nanocrystals to Perylene Bisimide

Abstract

Long-wavelength light penetrates deeply in a variety of substances and can induce selective excitation in condensed phases. Therefore, photofunctional materials that are responsive to long-wavelength light are essential. Ag2S nanocrystals (NCs), which are near-infrared-light (NIR)-responsive materials, have applications as NIR phosphors and photosensitizers. However, the excited-state dynamics of Ag2S NCs combined with aromatic molecules have not been elucidated to date. In this study, we synthesized perylene bisimide-coordinated Ag2S nanocrystals (PBI-Ag2S) and investigated the excited-state dynamics by subpicosecond-to-nanosecond transient absorption spectroscopy. When PBI-Ag2S is excited using a 530 nm light, where the excited-state dynamics of the PBI moiety is mainly probed, PBI radical anions are instantaneously produced by ultrafast hole transfer from PBI to Ag2S NCs. Moreover, PBI radical anions are formed even upon excitation with a 720-nm light, where only Ag2S NCs are selectively excited. This study is important for developing novel organic-inorganic nanohybrid photofunctional materials that utilize low-energy light efficiently for applications in photoredox catalysts, optoelectronic devices, and solar cells.