Ionic Field Screening in MAPbBr<sub>3</sub> Crystals Revealed from Remnant Sensitivity in X-ray Detection
Agustín O. Alvarez, Ferdinand Lédée, Marisé García‐Batlle, Pilar López-Varo, Eric Gros‐Daillon, Javier Mayén Guillén, Jean‐Marie Verilhac, Thibault Lemercier, Julien Zaccaro, Lluı́s F. Marsal, Germà García-Belmonte, Osbel Almora
Abstract
High Resolution Image Download MS PowerPoint Slide 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 (MAPbBr 3 ) 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.