Lattice dynamics and self-trapped excitons in the Cs2SnBr6double perovskites

Manh Ha Hoang; Duy Manh Le; Anh Thi Le; Quoc Khanh Nguyen; T Anh Thu Do; Truong Giang Ho; Minh Tan Man

doi:10.1088/1361-648X/ad3ac4

Lattice dynamics and self-trapped excitons in the Cs₂SnBr₆double perovskites

J Phys Condens Matter. 2024 Apr 15;36(28). doi: 10.1088/1361-648X/ad3ac4.

Authors

Manh Ha Hoang¹, Duy Manh Le^{2

3}, Anh Thi Le^{2

3

4}, Quoc Khanh Nguyen⁵, T Anh Thu Do⁶, Truong Giang Ho⁶, Minh Tan Man^{2

3}

Affiliations

¹ Hanoi Architectural University, Km 10 Nguyen Trai, Thanh Xuan, Hanoi, Vietnam.
² Institute of Theoretical and Applied Research, Duy Tan University, Hanoi 100000, Vietnam.
³ Faculty of Natural Sciences, Duy Tan University, Da Nang 550000, Vietnam.
⁴ Graduate University of Science and Technology, Vietnam Academy of Science and Technology, 18 Hoang Quoc Viet, Cau Giay, Hanoi, Vietnam.
⁵ Hanoi University of Industry, Hanoi, Vietnam.
⁶ Institute of Materials Science, Vietnam Academy of Science and Technology, 18 Hoang Quoc Viet, Cau Giay, Hanoi, Vietnam.

PMID: 38574677
DOI: 10.1088/1361-648X/ad3ac4

Abstract

Our study delved into the detailed investigation of Cs₂SnBr₆double perovskites, focusing on their electrical properties, lattice dynamics, and stability. The direct bandgap for Cs₂SnBr₆was estimated to be at 2.93 eV. One external translational mode of the Cs⁺lattice withT_2gsymmetry and three internal modes of the octahedral withA_1g,E_g, andT_2gsymmetries are defined by calculated lattice dynamics, experimental micro-Raman scattering. We show a correlation with first-principles calculations, validating using a band-structured electronic approach to understanding the behavior of charge carriers, and electron-phonon interactions in Cs₂SnBr₆. We propose that electron-vibration interactions result in self-trapped excitons (STEs) displaying significant Stokes shifts (0.508 eV) and broad-spectrum emission. Understanding the behavior of STEs is fundamental for their optoelectronic applications.

Keywords: Cs2SnBr6; Raman scattering; double perovskites; phonon dynamics; stokes shift energy.