Long-Lived Negative Photocharging in Colloidal CdSe Quantum Dots Revealed by Coherent Electron Spin Precession

• DOI: 10.1021/acs.jpclett.9b02341
• Publication Date: 2019-08-13T19:05:07Z
• Authors: Rongrong Hu; Zhen Wu; Yuanyuan Zhang; Dmitri R. Yakovlev; Pan Liang; Gang Qiang; Jiaxing Guo; Tianqing Jia; Zhenrong Sun; Manfred Bayer; Donghai Feng
• Keywords: Precession

Photoinduced charging in CdSe colloidal quantum dots (QDs) is investigated by time-resolved pump–probe spectroscopy that sensitive to electron spin polarization. This technique monitors the coherent dynamics of optically oriented electrons precessing around an external magnetic field. By addition 1-octanethiol QD solution toluene, extremely long-lived negative photocharging detected lives up 1 month N2 atmosphere and hours air at room temperature. 1-Octanethiol not only acts as a hole acceptor but also results reduction oxygen-induced photo-oxidation QDs, allowing air-stable photocharging. Two types states with different precession frequencies very lifetimes are identified. These findings have important implications for understanding photophysical processes nanostructures.