TY - JOUR

T1 - Exciton binding energy and the origin of yellow-light emission in CH3NH3PbBr3 single crystals

AU - Zhevstovskikh, I. V.

AU - Averkiev, N. S.

AU - Sarychev, M. N.

AU - Semenova, O. I.

AU - Tereshchenko, O. E.

N1 - This research was carried out within the state assignment No. 122021000039-4 and partially supported by the Ministry of Science and Higher Education of the Russian Federation (through the basic part of the government mandate, Project No. FEUZ-2023-0013 and program of strategic academic leadership “Priority 2030”).

PY - 2024

Y1 - 2024

N2 - Organic-inorganic lead halide perovskites have emerged in recent years as semiconductor materials for various optoelectronic and photovoltaic applications. The exciton binding energy is an important parameter because the formation of excitons can potentially hamper charge separation in solar cells. However, it remains a challenge to experimentally determine the exciton binding energy in hybrid bromine-based perovskites: the obtained values have a tens meV spread. Here we present in detail the near-band edge photoluminescence study in CH3NH3PbBr3 single crystals under different photoluminescence excitation densities with a 405 nm laser diode. We show that by using high laser excitation intensities it is possible to make a direct measurement of the exciton binding energy, which we find to be only 12 meV at low temperatures, lower than has been previously determined. In the low temperature orthorhombic phase, besides the free exciton emission at 2.25 eV, we observed the broad yellow-light emission at 2.16 eV, which exhibited a red shift with the increasing temperature and a blue shift with increasing laser excitation intensity. Based on the excitation power density and temperature dependence of the photoluminescence spectra, we interpreted yellow-light emission as a recombination of bound excitons and a donor-acceptor pair transition. The results obtained are essential for a better understanding of the electronic properties of these materials and provide a guideline for their further applications with improved performance.

AB - Organic-inorganic lead halide perovskites have emerged in recent years as semiconductor materials for various optoelectronic and photovoltaic applications. The exciton binding energy is an important parameter because the formation of excitons can potentially hamper charge separation in solar cells. However, it remains a challenge to experimentally determine the exciton binding energy in hybrid bromine-based perovskites: the obtained values have a tens meV spread. Here we present in detail the near-band edge photoluminescence study in CH3NH3PbBr3 single crystals under different photoluminescence excitation densities with a 405 nm laser diode. We show that by using high laser excitation intensities it is possible to make a direct measurement of the exciton binding energy, which we find to be only 12 meV at low temperatures, lower than has been previously determined. In the low temperature orthorhombic phase, besides the free exciton emission at 2.25 eV, we observed the broad yellow-light emission at 2.16 eV, which exhibited a red shift with the increasing temperature and a blue shift with increasing laser excitation intensity. Based on the excitation power density and temperature dependence of the photoluminescence spectra, we interpreted yellow-light emission as a recombination of bound excitons and a donor-acceptor pair transition. The results obtained are essential for a better understanding of the electronic properties of these materials and provide a guideline for their further applications with improved performance.

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U2 - 10.1103/PhysRevMaterials.8.034601

DO - 10.1103/PhysRevMaterials.8.034601

M3 - Article

VL - 8

JO - Physical Review Materials

JF - Physical Review Materials

SN - 2475-9953

IS - 3

M1 - 034601

ER -