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Pressure-Tuned Core/Shell Configuration Transition of Shell Thickness-Dependent CdSe/CdS Nanocrystals

Pengfei LvState Key Laboratory of Superhard Materials, College of Physics, Jilin University, Changchun 130012, ChinaYing SunState Key Laboratory of Superhard Materials, College of Physics, Jilin University, Changchun 130012, ChinaLaizhi SuiState Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, 457 Zhong Shan Road, Dalian 116023, ChinaZhiwei MaState Key Laboratory of Superhard Materials, College of Physics, Jilin University, Changchun 130012, ChinaKaijun YuanState Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, 457 Zhong Shan Road, Dalian 116023, ChinaGuorong WuState Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, 457 Zhong Shan Road, Dalian 116023, ChinaChuang LiuState Key Laboratory of Superhard Materials, College of Physics, Jilin University, Changchun 130012, ChinaRuijing FuState Key Laboratory of Superhard Materials, College of Physics, Jilin University, Changchun 130012, ChinaHanyu LiuState Key Laboratory of Superhard Materials, College of Physics, Jilin University, Changchun 130012, ChinaGuanjun XiaoState Key Laboratory of Superhard Materials, College of Physics, Jilin University, Changchun 130012, ChinaBo ZouState Key Laboratory of Superhard Materials, College of Physics, Jilin University, Changchun 130012, China

2020en

ABI

Annotatsiya

Pressure is adopted as a "clean" tool to achieve a core/shell configuration transition of CdSe/CdS nanocrystals (NCs) from quasi-type II to type I. The pressure-dependent photoluminescence (PL) spectra demonstrate a sudden decrease in PL intensity, because of the enhanced rate of exciton-exciton annihilation of type I structured CdSe/CdS NCs. Likewise, the large decrease in the PL lifetime with pressure confirms that the electron wave function mainly localizes into the CdSe core, indicating the decreased separation of electrons and holes in type I band alignment. We propose that pressure increases the conduction band energy of the CdS shell but hardly changes that of the CdSe core with almost both unchanged valence band energies, thus ultimately increasing the conduction band offsets between the CdSe core and CdS shell to form the type I core/shell configuration. Our studies elucidate the significance of external pressure in determining the electronic and optical properties of core/shell nanomaterials.

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Identifikatorlar

DOI: 10.1021/acs.jpclett.9b03650

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