Exciton dynamics in CsPbBr3 single crystal: LT splitting energy, exciton-polariton dispersion, and biexciton binding energy

Naoki Shimosako; Mizuki Kumamoto; Yui Muroga; Zihao Liu; Masato Sotome; Takashi Kondo; Hideyuki Kunugita; Kazuhiro Ema

doi:10.1063/5.0232604

Exciton dynamics in CsPbBr3 single crystal: LT splitting energy, exciton-polariton dispersion, and biexciton binding energy

J Chem Phys. 2024 Nov 7;161(17):174703. doi: 10.1063/5.0232604.

Authors

Naoki Shimosako¹, Mizuki Kumamoto², Yui Muroga², Zihao Liu^{3

4}, Masato Sotome³, Takashi Kondo^{3

4}, Hideyuki Kunugita², Kazuhiro Ema²

Affiliations

¹ Department of Electronics and Materials Science, Shizuoka University, 3-5-1, Johoku, Chuo-ku, Hamamatsu, Shizuoka 432-8011, Japan.
² Department of Engineering and Applied Sciences, Sophia University, 7-1 Kioi-cho, Chiyoda, Tokyo 102-8554, Japan.
³ Department of Materials Engineering, The University of Tokyo, Bunkyo, Tokyo 113-8654, Japan.
⁴ Research Center for Advanced Science and Technology, The University of Tokyo, Meguro, Tokyo 153-8904, Japan.

PMID: 39484907
DOI: 10.1063/5.0232604

Abstract

Metal halide perovskite materials (MHPs) are promising for several applications due to their exceptional properties. Understanding excitonic properties is essential for exploiting these materials. For this purpose, we focus on CsPbBr3 single crystals, which have higher crystal quality, are more stable, and have no Rashba effect at low temperatures compared to other 3D MHPs. We have estimated exciton energy positions, longitudinal-transverse splitting energy, and damping energy using low-temperature reflection spectra. Under high excitation intensity, two biexciton emissions (M-emission) and exciton-exciton scattering emission (P-emission) were observed. We assign the two M-emissions to the emission to the states of longitudinal and transverse excitons, i.e., ML and MT emissions. From the energy position of the MT emission, the biexciton binding energy has been estimated to be ∼2 meV. By analyzing P-emission obtained from the back side of the sample, we have estimated the exciton binding energy to be 17.8-23.7 meV. This estimation minimizes the influence of the wavenumber distribution in the scattering process. In addition, time-resolved transmittance measurements using pulsed white light have revealed the group velocity dispersion. Comparing experimental results with theoretical calculations using the Lorentz model clarifies that exciton dynamics in CsPbBr3 can be described with a simple Lorentz model. These insights enhance the understanding of exciton behavior and support the development of exciton-based devices using MHPs.