Atomistic Surface Passivation of CH3NH3PbI3 Perovskite Single Crystals for Highly Sensitive Coplanar-Structure X-Ray Detectors.

Yilong Song,Xiaohui Li,Weihui Bi,Zisheng Wang,Anran Wang,Mingwei Hao,Yifei Kang,Hanming Li,Liqi Li,Qingfeng Dong,Yanjun Fang,Deren Yang

doi:10.34133/2020/5958243

Yilong Song, Xiaohui Li + Show 10 more

Open Access

https://doi.org/10.34133/2020/5958243

Copy DOI

Abstract

Organic-inorganic halide perovskites (OIHPs) are recognized as the promising next-generation X-ray detection materials. However, the device performance is largely limited by the ion migration issue of OIHPs. Here, we reported a simple atomistic surface passivation strategy with methylammonium iodide (MAI) to remarkably increase the ion migration activation energy of CH3NH3PbI3 single crystals. The amount of MAI deposited on the crystal surface is finely regulated by a self-assemble process to effectively suppress the metallic lead defects, while not introducing extra mobile ions, which results in significantly improved dark current stability of the coplanar-structure devices under a large electric field of 100 V mm−1. The X-ray detectors hence exhibit a record-high sensitivity above 700,000 μC Gyair‐1 cm‐2 under continuum X-ray irradiation with energy up to 50 keV, which enables an ultralow X-ray detection limit down to 1.5 nGyair s−1. Our findings will allow for the dramatically reduced X-ray exposure of human bodies in medical imaging applications.

Highlights

High-performance X-ray detectors are increasingly important in many fields, including medical imaging, security monitoring, material inspection, and scientific research. [1,2,3,4] Especially in the medical diagnosis field, the X-ray-based medical imaging techniques such as X-ray radiography and computed tomography (CT) are gradually becoming the routine methods for disease diagnosis
For regular organic-inorganic halide perovskites (OIHPs)-based detectors, usually, a small electric field is applied across the perovskite layer to avoid the ion migration effect for better operational stability
The use of single crystal (SC) can eliminate the fast ion migration pathways caused by grain boundaries, the surface of the SC with a high density of defects can still behave as an ion migration channel, especially for the coplanar-structure device in which the electric field is located close to the crystal surface (Figure 1(d))

Summary

Introduction

High-performance X-ray detectors are increasingly important in many fields, including medical imaging, security monitoring, material inspection, and scientific research. [1,2,3,4] Especially in the medical diagnosis field, the X-ray-based medical imaging techniques such as X-ray radiography and computed tomography (CT) are gradually becoming the routine methods for disease diagnosis. For a semiconductor-type X-ray detector, which directly converts incident X-ray into electron-hole pairs, the sensitivity of the device is closely related to the attenuation capability and the electrical transport properties of the active material. This requires the material to possess both a high atomic number for large X-ray stopping power and a large mobility-lifetime (μτ) product to allow the efficient charge collection.

Methods

Results

Conclusion