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arXiv · 2505.15565

Exciton Bohr radius of lead halide perovskites for photovoltaic and light-emitting applications

Hyun Myung Jang·Kyung Yeon Jang·Song Hee Lee·Jinwoo Park·Tae-Woo Lee
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Abstract

Exciton Bohr radius (a_B) and exciton binding energy (E_b) of metal halide perovskites are two prime quantities in their applications to both light-emitting diode displays and photovoltaic devices. We develop a reliable theoretical method of simultaneously finding a_B and {\epsilon}_r^c (dielectric constant) based on the net exciton energy above the bulk band gap. It is estimated that a_B under the dielectric confinement is substantially smaller than a_B in the absence of dielectric confinement: 4.36 nm vs. 5.61 nm in the case of CH3NH3PbBr3. We attribute the enhanced a_B to variations of {\epsilon}_r^c and the electron-hole correlation energy. We also develop a simple method of finding E_b based on the same net exciton energy. Using this, we attribute the well-known difference in E_b between organic bromide perovskites and iodide counterparts to {\epsilon}_r^c and explain that iodide perovskites are more suited than bromide counterparts in photovoltaic applications, which require smaller E_b for efficient charge-carriers transport.

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Hyun Myung Jang, Kyung Yeon Jang, Song Hee Lee, Jinwoo Park, Tae-Woo Lee. 2025-05-21. Exciton Bohr radius of lead halide perovskites for photovoltaic and light-emitting applications. https://arxiv.org/abs/2505.15565

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