Ionic Field Screening in MAPbBr3 Crystals Revealed from Remnant Sensitivity in X-ray Detection

Identifier:  imarina:9320439

Handle: https://hdl.handle.net/20.500.11797/imarina9320439

Authors:  Alvarez, Agustin O; Alvarez, Agustin O; Ledee, Ferdinand; Garcia-Batlle, Marise; Lopez-Varo, Pilar; Gros-Daillon, Eric; Guillen, Javier Mayen; Verilhac, Jean-Marie; Lemercier, Thibault; Zaccaro, Julien; Marsal, Lluis F; Marsal, Lluis F; Garcia-Belmonte, Germa; Almora, Osbel

Abstract:
Research on metal halide perovskites as absorbers for X-ray detection is an attractive subject due to the optimal optoelectronic properties of these materials for high-sensitivity applications. However, the contact degradation and the long-term instability of the current limit the performance of the devices, in close causality with the dual electronic-ionic conductivity of these perovskites. Herein, millimeter-thick methylammonium-lead bromide (MAPbBr3) single and polycrystalline samples are approached by characterizing their long-term dark current and photocurrent under X-ray incidence. It is shown how both the dark current and the sensitivity of the detectors follow similar trends at short-circuit (V = 0 V) after biasing. By performing drift-diffusion numerical simulations, it is revealed how large ionic-related built-in fields not only produce relaxations to equilibrium lasting up to tens of hours but also continue to affect the charge kinetics under homogeneous low photogeneration rates. Furthermore, a method is suggested for estimating the ionic mobility and concentration by analyzing the initial current at short-circuit and the characteristic diffusion times.