Ionic accumulation and depletion space-charge zones at metal halide perovskite contacts from device numerical simulations

Identifier:  imarina:9464094

Handle: https://hdl.handle.net/20.500.11797/imarina9464094

Authors:  Garcia-Belmonte, G; Almora, O

Abstract:
The inherent ion migration in metal halide perovskite is known to induce instabilities into the operation of solar cells and radiation detectors based on these compounds. For instance, dark current slow drift with time has been identified among the major drawbacks for X- and gamma-ray detectors to satisfy industrial requirements. Conversion efficiency in photovoltaic devices usually exhibits significant reduction upon continuous illumination. In both cases, the formation of ion-related space-charge zones at the vicinity of the electrode interfaces (electrode polarization upon biasing) is believed to play a major role in the degradation of the device functioning. By using 1D numerical simulation tools, two dissimilar charged structures are identified after voltage application in the steady state: a narrow and huge ion accumulation near one electrode compensated by a spatially extended depletion zone at the opposite one. Ion accumulation zone width correlates with the ionic Debye length for ion concentration below a certain limit. In addition, more extended ion depletion zones follow the dependencies usually encountered in semiconductor contacts inversely proportional to the square root of ion concentration and proportional to the square root of voltage. Deviations from classical models are also discussed in relation to the theoretical assumptions.