Reducing the leakage current for a CsPbBr3 detector via asymmetric area electrodes and heterostructures

As a typical representative of all-inorganic lead halide perovskites, cesium lead bromine (CsPbBr3) has been regarded as the workhorse of next-generation room temperature X-ray detectors in recent years. Because of their promising photo-electronic performance, CsPbBr3 single crystals show a wide variety of applications such as in medical imaging and product inspection. An X-ray detector with high sensitivity would be able to increase the signal to noise ratio and reduce the X-ray dose rate. A perfect performance is assumed to occur when the detectors have low leakage current. Herein, we describe two strategies to reduce the leakage current and get a more stable baseline. First, we discuss a new device Au/CsPbBr3/Au with asymmetric area electrodes. We made Au(1)/CsPbBr3/Au(4), Au(1.5)/CsPbBr3/Au(4) and Au(3)/CsPbBr3/Au(4) to represent these above devices, where the numbers in brackets refer to the diameter of the electrodes. Compared with devices with symmetric area electrodes, Au(4)/CsPbBr3/Au(4), these wafers were proved to be effective to suppress leakage current and improve the stability of the devices. At a bias of 50 V, Au(1)/CsPbBr3/Au(4) shows the lowest leakage current, 3.2 nA under X-rays. Then, we also fabricate heterojunction devices Au/CuI/CsPbBr3/Au by coating with a CuI layer. Compared with the photoconductive devices, these heterojunction devices developed less baseline drift and showed better stability. Our study on reducing leakage current and stabling the baseline of the devices will provide a significant approach to enhance the performance of CsPbBr3 detectors.