Investigation of structural and optical properties of MAPbBr3 monocrystals under fast electron irradiation

Abstract

Halide perovskites have demonstrated great potential for photovoltaics and detector applications, due to the strong absorption, large mobility lifetime product, structural defect tolerance, and wide range of chemical compositions with high Z atoms. Ionizing radiation sensing is one of the emerging directions for the use of halide perovskites, which already demonstrated high radiation hardness. In this work, we study the impact of radiation stress on MAPbBr₃ perovskite crystals in order to assess further high-energy detection applications. We investigate the changes in structural and optical properties of perovskite crystals induced by e-beam irradiation with high flux (10¹⁵ electrons per cm², energy 5 MeV) and an extremely high dose (25 MRAD). Ellipsometry measurements demonstrated a strong increase of the Urbach tails related to radiation-induced defects. A trap-induced Fermi level pinning at +0.56 eV was observed by Kelvin probe microscopy analysis of the irradiated MAPbBr₃ monocrystals with respect to pristine crystals. However, X-ray diffraction analysis and optical depth analysis with two-photon excitation microscopy photoluminescence reveal that, despite the large irradiation dose, the structural and optical properties are stable. This clearly shows that MAPbBr crystals are stable for high energy applications.