Detection of X-Rays by Solution-Processed Cesium-Containing Mixed Triple Cation Perovskite Thin Films

Materials and technology development for designing innovative and efficient X-ray radiation detectors is of utmost importance for a wide range of applications ranging from security to medical imaging. Here, highly sensitive direct X-ray detectors based on novel cesium (Cs)-based triple cation mixed halide perovskite thin films are reported. Despite being in a thin film form, the devices exhibit a remarkably high X-ray sensitivity of (3.7 +/- 0.1) mu C Gy(-1) cm(-2) under short-circuit conditions. At a small reverse bias of 0.4 V, the sensitivity further increases by orders of magnitude reaching a record value of (97 +/- 1) mu C Gy(-1) cm(-2) which surpasses state-of-the-art inorganic large-area detectors (a-Se and poly-CZT). Based on detailed structural, electrical, and spectroscopic investigations, the exceptional sensitivity of the triple cation Cs perovskite is attributed to its high ambipolar mobility-lifetime product as well as to the formation of a pure stable perovskite phase with a low degree of energetic disorder, due to an efficient solution-based alloying of individual n- and p-type perovskite semiconductors.