Multiphoton excited singlet/triplet mixed self-trapped exciton emission

Rui Zhou; Laizhi Sui; Xinbao Liu; Kaikai Liu; Dengyang Guo; Wenbo Zhao; Shiyu Song; Chaofan Lv; Shu Chen; Tianci Jiang; Zhe Cheng; Sheng Meng; Chongxin Shan

doi:10.1038/s41467-023-36958-3

Multiphoton excited singlet/triplet mixed self-trapped exciton emission

Nat Commun. 2023 Mar 10;14(1):1310. doi: 10.1038/s41467-023-36958-3.

Authors

Rui Zhou^#¹, Laizhi Sui^#², Xinbao Liu³, Kaikai Liu⁴, Dengyang Guo^{1

5}, Wenbo Zhao¹, Shiyu Song¹, Chaofan Lv¹, Shu Chen¹, Tianci Jiang^{6

7}, Zhe Cheng^{6

7}, Sheng Meng³, Chongxin Shan⁸

Affiliations

¹ Henan Key Laboratory of Diamond Optoelectronic Materials and Devices, School of Physics and Microelectronics, Zhengzhou University, Zhengzhou, P. R. China.
² State Key Laboratory of Molecular Reaction Dynamics and Dalian Coherent Light Source, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, P. R. China.
³ Institute of Physics, Chinese Academy of Sciences, Beijing, China.
⁴ Henan Key Laboratory of Diamond Optoelectronic Materials and Devices, School of Physics and Microelectronics, Zhengzhou University, Zhengzhou, P. R. China. liukaikai@zzu.edu.cn.
⁵ Department of Physics, Cavendish Laboratory, University of Cambridge, Cambridgeshire, UK.
⁶ Department of Pulmonary and Critical Care Medicine, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, P. R. China.
⁷ Henan Key Laboratory for Pharmacology of Liver Diseases, Zhengzhou, P. R. China.
⁸ Henan Key Laboratory of Diamond Optoelectronic Materials and Devices, School of Physics and Microelectronics, Zhengzhou University, Zhengzhou, P. R. China. cxshan@zzu.edu.cn.

^# Contributed equally.

Abstract

Multiphoton excited luminescence is of paramount importance in the field of optical detection and biological photonics. Self-trapped exciton (STE) emission with self-absorption-free advantages provide a choice for multiphoton excited luminescence. Herein, multiphoton excited singlet/triplet mixed STE emission with a large full width at half-maximum (617 meV) and Stokes shift (1.29 eV) has been demonstrated in single-crystalline ZnO nanocrystals. Temperature dependent steady state, transient state and time-resolved electron spin resonance spectra demonstrate a mixture of singlet (63%) and triplet (37%) mixed STE emission, which contributes to a high photoluminescence quantum yield (60.5%). First-principles calculations suggest 48.34 meV energy per exciton stored by phonons in the distorted lattice of excited states, and 58 meV singlet-triplet splitting energy for the nanocrystals being consistent with the experimental measurements. The model clarifies long and controversial debates on ZnO emission in visible region, and the multiphoton excited singlet/triplet mixed STE emission is also observed.