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Updated: Dec 26, 2025
08:12
Low Pressure Vapor-assisted Solution Process for Tunable Band Gap Pinhole-free Methylammonium Lead Halide Perovskite Films
Published on: September 8, 2017
9.9K
Temperature-Dependent Optical Band Gap in CsPbBr3, MAPbBr3, and FAPbBr3 Single Crystals
Giovanni Mannino1, Ioannis Deretzis1, Emanuele Smecca1
1CNR-IMM, Zona Industriale Strada VIII No. 5, 95121 Catania, Italy.
The Journal of Physical Chemistry Letters
|March 10, 2020
Summary
We investigated the optical properties of three lead bromide perovskite single crystals, revealing high optical quality and distinct behaviors during structural phase transitions. Octahedral tilting and thermal expansion significantly influence their band gaps.
Area of Science:
- Materials Science
- Solid State Physics
- Optoelectronics
Background:
- Single crystals are crucial for understanding bulk halide perovskite properties.
- Lead bromide perovskites (MAPbBr₃, CsPbBr₃, FAPbBr₃) are promising optoelectronic materials.
- Their optical properties are sensitive to temperature and crystal structure.
Purpose of the Study:
- To investigate the dielectric function and band gap of MAPbBr₃, CsPbBr₃, and FAPbBr₃ single crystals.
- To analyze the influence of temperature and structural phase transitions on optical properties.
- To correlate optical data with theoretical calculations for a deeper understanding.
Main Methods:
- Spectroscopic ellipsometry was used to measure the dielectric function from 1-5 eV.
- Temperature-dependent measurements were performed from 183 K to 440 K.
- Critical point analysis and Density Functional Theory (DFT) calculations were employed.
Main Results:
- All three crystals exhibited extremely low sub-band gap absorption, indicating high optical quality.
- Band gap values were extracted, with Tauc-based methods found to underestimate them.
- Distinct optical behaviors were observed during the orthorhombic-tetragonal and tetragonal-cubic phase transitions.
Conclusions:
- Octahedral tilting plays a key role in determining the band gap at specific temperatures.
- Thermal expansion differences influence the temperature dependence slope of the band gap.
- The study provides insights into the fundamental optoelectronic properties of lead bromide perovskites.
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