Prof. Yucheng Liu

Shaanxi Normal University, China

Research Areas: Semiconductor, photovoltaic and photoelectronic devices

Speech Title: Large Size and High-Quality Perovskite Single Crystal for High-Performance X-ray Imaging   

Abstract

Low ionic migration is required for a semiconductor material to realize stable high-performance X-ray detection. In this work, we report successful controlled incorporation of not only methylammonium (MA⁺) and cesium (Cs⁺) cations but also bromine (Br^-) anions into the FAPbI₃ lattice to grow inch-sized stable perovskite single crystal (FAMACs SC). The smaller cations and anions, comparing to the original FA⁺ and I^- help release lattice stress so that the FAMACs SC shows lower ion migration, enhanced hardness, lower trap density, longer carrier lifetime and diffusion length, higher charge mobility and thermal stability, and better uniformity. Therefore, X-ray detectors made of the superior FAMACs SCs show the highest sensitivity of (3.5 ± 0.2) × 10⁶ μC Gy_air^-1 cm^-2, about 29 times higher than the latest record of 1.22 × 10⁵ μC Gy_air^-1 cm^-2 for polycrystalline MAPbI₃ wafer under the same 40 keV X-ray radiation. Furthermore, the FAMACs SC X-ray detector shows a low detection limit of 42 nGy s^-1, stable dark current, and photocurrent response. Finally, we demonstrate using the FAMACs SC detector realize high contrast X-ray imaging. The effective triple-cation mixed halide strategy and the high crystalline quality make the present FAMACs SCs promising for next-generation X-ray imaging system.

Biography

Yucheng Liu received his Bachelor’s degree from Inner Mongolia Normal University in 2014, and Ph.D. in Material Science from Shaanxi Normal University in 2020 supervised by Prof. Shengzhong (Frank) Liu During 2014–2020. He joined Prof. Mercouri G. Kanatzidis’s group as a Visiting Scholar at Northwestern University (USA) in 2019. Now he is a professor at Shaanxi Normal University. His research mainly focuses on single crystalline perovskite materials and devices, including perovskite solar cell, single crystal based photoelectronic devices, like photodetectors and X-ray detectors for imaging.