Deposition-Dependent Excitonic Properties of Spin-Coated CsPbBr3 Thin Films Revealed by Temperature-Dependent Optical Spectroscopy.
Year: 2026
Type: preprint
Abstract: Temperature dependence of the optical properties of CsPbBr3 perovskites prepared by spin coating is studied. Absorbance and photoluminescence spectra were acquired at controlled temperature varying from room temperature to 20 K. In the case of absorbance, the Elliott model for excitonic absorbance was considered, allowing obtaining parameters such as bandgap energy, exiton binding energy, and Stokes shift, among others. The bandgap energy increases with temperature, against what is observed in conventional tetragonal semiconductors. The exciton binding energy also increases with temperature as expected from its dependence with reduced exciton effective mass and dielectric constant. The Stokes shift follows Guriolli´s model for carrier thermalization in photoluminescence spectra, indicating the free excitonic recombination as its origin. Other models were also studied, such as the Segall function for the Full Width at Half Maximum of the photoluminescence spectra, which shows that the dominant term at higher temperatures is the exciton optical phonon coupling. Arrhenius function for the area of the photoluminescence spectral intensity indicates two channels of exciton dissociation. At low temperatures the Urbach energy is very low, and gives phonon energies compatible with the one obtained from Segall model. It was observed that certain parameters, such as the excitonic binding energy and the Urbach energy, show appreciable variation with the number of cycles of the sample synthesis process. The sample synthesized with 5 cycles presents an optimal balance between low disorder, less exciton-phonon coupling and favorable excitonic parameters.
Source: ChemRxiv
Language: English
Subfield: Electrical and Electronic Engineering
Field: Engineering
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W7220388324