Towards efficient photoinduced charge separation in carbon nanodots and TiO2 composites in the visible region

Abstract

The visible photoinduced electrons and holes in CDs-V/TiO ₂ composites could be effectively separated, indicating that a well performing CD-based photovoltaic system could be realized.

Abstract

In this work, photoinduced charge separation behaviors in non-long-chain-molecule-functionalized carbon nanodots (CDs) with visible intrinsic absorption (CDs-V) and TiO ₂ composites were investigated. Efficient photoinduced electron injection from CDs-V to TiO ₂ with a rate of 8.8 × 10 ⁸ s ⁻¹ and efficiency of 91% was achieved in the CDs-V/TiO ₂ composites. The CDs-V/TiO ₂ composites exhibited excellent photocatalytic activity under visible light irradiation, superior to pure TiO ₂ and the CDs with the main absorption band in the ultraviolet region and TiO ₂ composites, which indicated that visible photoinduced electrons and holes in such CDs-V/TiO ₂ composites could be effectively separated. The incident photon-to-current conversion efficiency (IPCE) results for the CD-sensitized TiO ₂ solar cells also agreed with efficient photoinduced charge separation between CDs-V and the TiO ₂ electrode in the visible range. These results demonstrate that non-long-chain-molecule-functionlized CDs with a visible intrinsic absorption band could be appropriate candidates for photosensitizers and offer a new possibility for the development of a well performing CD-based photovoltaic system.