Analytical Modelling of Photocurrent in Double Perovskite Cs2agbibr6 X-Ray Detectors

This work has developed a theoretical model to investigate the mechanisms of nonlinear steady-state photocurrent versus dose rate characteristics in Cs2AgBiBr6 X-ray detectors. The photocurrent analysis on Cs2AgBiBr6 X-ray detector shows that there is a photocurrent gain, primarily due to the presence of dark current. Charge injection from the metal contacts is the primary source of dark current in Cs2AgBiBr6. The nonlinear dark current versus dose rate characteristics are mainly responsible for the nonlinear steady-state photocurrent in Cs2AgBiBr6. The accumulation of X-ray induced ions near the electrodes elevates the metal/perovskite interface electric field, increasing the charge injection. The Schottky barrier height for charge injection is found to be dependent on the applied X-ray dose as well. The comparison of the model with the experimental results reveals the accumulated ion concentrations and effective barrier heights.