Chuang Ma, Lili Gao,* Zhuo Xu, Xiaotong Li, Xin Song, Yucheng Liu, Tinghuan Yang, Haojin Li,

Yachao Du, Guangtao Zhao, Xinmei Liu, Mercouri G. Kanatzidis,* Shengzhong Frank Liu,*

and Kui Zhao*

ABSTRACT:

Metal-halide perovskitoids with corner-, edge-, and face-sharing

octahedra provide a fertile “playground” for structure modulation. With low defect

density, low ion migration, and high intrinsic stability, two-dimensional (2D)

perovskitoid single crystals are expected to be ideal materials for room-temperature

semiconductor detectors (RTSDs) as high-energy radiation. However, there is no report

yet on the use of 2D perovskitoid single crystals for X-ray detection, as well as on how

the halide-modulated molecular assembly would affect their structure and properties.

Herein, based on an amidino-based organic spacer, we successfully synthesized a novel

family of centimeter-sized 2D perovskitoid single crystals, (3AP)PbX4 (3AP = 3-

amidinopyridine, X = Cl, Br, and I). This is the first time that centimeter-sized 2D

perovskitoid single crystals are demonstrated for X-ray photoresponse. Detailed

investigations reveal a unique crystal packing with corner-sharing and edge-sharing octahedra of inorganic frameworks and 3AP

cations lying between adjacent inorganic layers in a parallel and antisymmetric manner. Changing the halide from I to Br and Cl

results in greater Pb−X−Pb angles and stronger hydrogen bonding in perovskitoids and therefore consequently a better elastic

recovery under stress, a more efficient charge transport in the inorganic layer, and a lower ionic migration. By varying halide

substitution, an efficient X-ray photoresponse is achieved with a sensitivity up to 791.8 μC Gyair−1 cm−2 for (3AP)PbCl4 and a low

detection limit of 1.54 μGyair s−1. These results reveal that the large 2D perovskitoid single crystals provide a promising platform for

high performance optoelectronics.

https://doi.org/10.1021/acs.chemmater.1c03832