X‐Site Substituted 2D Cs2Pb(SCN)2Br2 Perovskites for X‐Ray Detection

Abstract

Abstract2D Ruddlesden–Popper (RP) perovskites have been intensively investigated due to their superior stability and outstanding optoelectrical properties. However, investigations on 2D RP perovskites are mainly focused on A‐site substituted perovskites and few reports are on X‐site substituted perovskites especially in X‐ray detection field. Here, X‐site substituted 2D RP perovskite Cs2Pb(SCN)2Br2 polycrystalline wafers are prepared and systematically studied for X‐ray detection. The obtained wafers show a large resistivity of 2.0 × 1010 Ω cm, a high ion activation energy of 0.75 eV, a small current drift of 2.39 × 10−6 nA cm−1 s−1 V−1, and charge carrier mobility‐lifetime product under X‐ray as high as 1.29 × 10−4 cm2 V−1. These merits enable Cs2Pb(SCN)2Br2 wafer detectors with a sensitivity of 216.3 µC Gyair−1 cm−2, a limit of detection of 42.4 nGyair s−1, and good imaging ability with high spatial resolution of 1.08 lp mm−1. In addition, Cs2Pb(SCN)2Br2 wafer detectors demonstrate excellent operational stability under high working field up to 2100 V cm−1 after continuous X‐ray irradiation with a total dose of 45.2 Gyair. The promising features such as short octahedral spacing and weak ion migration will open up a new perspective and opportunity for SCN‐based 2D perovskites in X‐ray detection.