Strong Triplet-Exciton-LO-Phonon Coupling in Two-Dimensional Layered Organic-Inorganic Hybrid Perovskite Single Crystal Microflakes

Yunuan Wang; Feilong Song; Yu Yuan; Jianchen Dang; Xin Xie; Sibai Sun; Sai Yan; Yanbing Hou; Zhidong Lou; Xiulai Xu

doi:10.1021/acs.jpclett.1c00342

Strong Triplet-Exciton-LO-Phonon Coupling in Two-Dimensional Layered Organic-Inorganic Hybrid Perovskite Single Crystal Microflakes

J Phys Chem Lett. 2021 Mar 4;12(8):2133-2141. doi: 10.1021/acs.jpclett.1c00342. Epub 2021 Feb 24.

Authors

Yunuan Wang^{1

2}, Feilong Song^{1

3}, Yu Yuan^{1

3}, Jianchen Dang^{1

3}, Xin Xie^{1

3}, Sibai Sun^{1

3}, Sai Yan^{1

3}, Yanbing Hou², Zhidong Lou², Xiulai Xu^{1

3

4}

Affiliations

¹ Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China.
² Key Laboratory of Luminescence and Optical Information, Ministry of Education, Beijing Jiaotong University, Beijing 100044, China.
³ CAS Center for Excellence in Topological Quantum Computation and School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100049, China.
⁴ Songshan Lake Materials Laboratory, Dongguan, Guangdong 523808, China.

PMID: 33625855
DOI: 10.1021/acs.jpclett.1c00342

Abstract

Two-dimensional (2D) layered hybrid perovskites provide an ideal platform for studying the properties of excitons. Here, we report on a strong triplet-exciton and longitudinal-optical (LO) phonon coupling in 2D (C₆H₅CH₂CH₂NH₃, PEA)₂PbBr₄ perovskites. The triplet excitons exhibit strong photoluminescence (PL) in thick perovskite microflakes, and the PL is not detectable for monolayer microflakes. The coupling strength of the triplet exciton-LO phonon is approximately two to three times greater than that of the singlet exciton-LO phonon with a LO phonon energy of about 21 meV. This difference might due to the different locations of singlet excitons located in the well and triplet excitons located in the barrier in the 2D layered perovskite. Revealing the strong coupling of triplet exciton-LO phonon provides a fundamental understanding of many-body interaction in hybrid perovskites, which is useful to develop and optimize the optoelectronic devices based on 2D perovskites in the future.