Polycrystalline Formamidinium Lead Bromide X-ray Detectors

Suad Alghamdi,Douglas Wolfe,Justin Reiss,Robert Moss,Stephanie Bennett,Carol Crean,Joydip Ghosh,Harry Gibbard,Paul Sellin

doi:10.3390/app12042013

Suad Alghamdi, Douglas Wolfe + Show 7 more

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https://doi.org/10.3390/app12042013

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Abstract

We have investigated the performance of formamidinium lead bromide (FAPbBr3) perovskite X-ray detectors fabricated from polycrystalline material that is pressed into a pellet at high pressures. FAPbBr3 has been shown to exhibit a remarkable combination of electrical and physical properties, such that mechanically-formed polycrystalline pellets exhibit good charge transport properties suitable for use as X-ray detectors. We characterise the morphology and structure of FAPbBr3 pellets using photoluminescence (PL), electron microscopy (SEM) and X-ray diffraction (XRD), and demonstrate an improvement in the microstructure, density, and charge transport performance of the material as the pressure is increased from 12 MPa to 124 MPa. The use of annealing of the pellets after pressing also improves the stability and charge transport performance of the devices. Using a 40 kV X-ray beam, a maximum X-ray sensitivity of 169 µC Gy−1 cm−2 was measured, and the fast time response of the devices was demonstrated using a chopped X-ray beam.

Highlights

In recent years, lead halide perovskites (LHPs) have attracted much attention due to their success in various applications such as light emitting devices [1], photovoltaic devices [2], and photodetectors [3]
In this work we report the performance of polycrystalline FAPbBr3 used as an energy integrating X-ray detector operating in a photoconductive mode
We have demonstrated the high sensitivity of FAPbBr3 polycrystalline X-ray detectors based on polycrystalline material produced using the relatively low-cost method of solution growth followed by mechanical grinding and pressing of pellets

Summary

Introduction

Lead halide perovskites (LHPs) have attracted much attention due to their success in various applications such as light emitting devices [1], photovoltaic devices [2], and photodetectors [3]. The species X is a halogen atom such as I, Cl, or Br. Perovskite materials have a three-dimensional network structure of Pb2+ cations. 6 coordinated with a halide species, and surrounded by 12 coordinated cations. We report the X-ray detection performance of organic LHP material containing the FA molecule. In FA-based LHPs the strength and the extension of the hydrogen bonds between the atoms (N-H-X) affects the microscopic dynamics of the organic cation [4–6]. Pressure can alter the orientation of the organic cation and the length of the hydrogen bond between the atoms

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