Trap-Mediated Sensitization Governs Near-Infrared Emission from Yb3+-Doped Mixed-Halide CsPbClxBr3- x Perovskite Nanocrystals

Nikita V Tepliakov; Anastasiia V Sokolova; Danila A Tatarinov; Xiaoyu Zhang; Weitao Zheng; Aleksandr P Litvin; Andrey L Rogach

doi:10.1021/acs.nanolett.3c04881

Trap-Mediated Sensitization Governs Near-Infrared Emission from Yb³⁺-Doped Mixed-Halide CsPbCl_xBr_{3- x} Perovskite Nanocrystals

Nano Lett. 2024 Mar 20;24(11):3347-3354. doi: 10.1021/acs.nanolett.3c04881. Epub 2024 Mar 7.

Authors

Nikita V Tepliakov^{1

2}, Anastasiia V Sokolova³, Danila A Tatarinov², Xiaoyu Zhang⁴, Weitao Zheng⁴, Aleksandr P Litvin^{2

4}, Andrey L Rogach^{3

5}

Affiliations

¹ Department of Materials and The Thomas Young Centre for Theory and Simulation of Materials, Imperial College London, London SW7 2AZ, United Kingdom.
² PhysNano Department, ITMO University, Saint-Petersburg 197101, Russia.
³ Department of Materials Science and Engineering, City University of Hong Kong, Hong Kong SAR 999077, P. R. China.
⁴ Key Laboratory of Automobile Materials MOE, School of Material Science & Engineering, Jilin University, Changchun 130012, P. R. China.
⁵ Centre for Functional Photonics (CFP), City University of Hong Kong, Hong Kong SAR 999077, P. R. China.

PMID: 38451030
DOI: 10.1021/acs.nanolett.3c04881

Abstract

Understanding the photosensitization mechanisms in Yb³⁺-doped perovskite nanocrystals is crucial for developing their anticipated photonic applications. Here, we address this question by investigating near-infrared photoluminescence of Yb³⁺-doped mixed-halide CsPbCl_xBr_3-x nanocrystals as a function of temperature and revealing its strong dependence on the stoichiometry of the host perovskite matrix. To explain the observed experimental trends, we developed a theoretical model in which energy transfer from the perovskite matrix to Yb³⁺ ions occurs through intermediate trap states situated beneath the conduction band of the host. The developed model provides an excellent agreement with experimental results and is further validated through the measurements of emission saturation at high excitation powers and near-infrared photoluminescence quantum yield as a function of the anion composition. Our findings establish trap-mediated energy transfer as a dominant photosensitization mechanism in Yb³⁺-doped CsPbCl_xBr_3-x nanocrystals and open up new ways of engineering their optical properties for light-emitting and light-harvesting applications.

Keywords: Yb3+-doped perovskite nanocrystals; bandgap engineering; near-infrared emission; quantum cutting; temperature-dependent photoluminescence; trap-mediated energy transfer.