Nuo Bu,a Shanshan Jia,a Yingrui Xiao,a Haojin Li,a Nan Li,a Xinmei Liu,a

Zhou Yang, *a Kui Zhao *a and Shengzhong (Frank) Liu *

ABSTRACT:

Lead-free perovskites are promising for next-generation bio-friendly X-ray detector materials, while it
remains a challenge to fabricate high-quality wafers at a macroscopic scale using a readily scalable
method. Herein, a solvent-free mechanochemical fabrication method is developed to produce inch-size
lead-free perovskite Cs3Bi2I9 crystalline-wafers. It is surprising to see that these polycrystalline wafers
exhibit near-intrinsic properties, and more specifically, the apparent trap density is measured to be as
low as 5.26  1010 cm3, essentially the same as that of their single-crystal counterparts. Therefore, the
X-ray detector fabricated on the Cs3Bi2I9 wafer delivers high sensitivity up to 230.46  19.86 mC Gyair1 cm2
and a detection limit as low as 61.25 nGyair s1 under a 40 kV X-ray source and 40 V mm1 electric field. This
research provides a readily scalable method for fabricating large perovskite wafers with near-intrinsic properties
for general commercial applications.

https://doi.org/
10.1039/d2tc00599a