Balance lead in solution-processed CH3NH3PbBrxCl(3−x) single crystals for high performance X-ray detection

Abstract

Organometallic perovskites MAPbX3 (MA = CH3NH3 and X = I, Br or Cl) are considered as potential materials for X-ray and gamma ray detection due to its high Z atom, large mobility-lifetime product and growth from solution. However, perovskites with one kind halide own numbers of free charges and yielded unbearable noise current. In this work, we grow perovskite single crystals (PSC) with different halide ratio and find the MAPbBr2.5Cl0.5 PSC shows outstanding performance in electric properties. Through energy dispersive X-ray spectrum, vacancy and excess of Pb is thought as the main cause of free charges. The atomic ratio between halide and Pb as 3 in MAPbBr2.5Cl0.5 PSC and its large resistivity 5.6 × 108 Ω cm and 160 cm2 V−1 s−1 high mobility are measured. Thanks to the smaller noise current, higher electric field could be established for higher charges collect efficiency. As a result, compared with pristine perovskite single crystals, improved X-ray detection performance is demonstrated. This work provides useful information to achieve high performance X-ray detectors based on organometallic perovskites.