Heterojunction structures for reduced noise in large-area and sensitive perovskite x-ray detectors

Abstract

Polycrystalline perovskites can be readily fabricated into large areas using solution depositions; however, they suffer from large dark currents that are tens to hundreds times higher than industrially relevant values, limiting their application in low-dose x-ray detection. Here, we show that the application of a heterojunction structure into polycrystalline films significantly reduces the dark current density by more than 200 times to subnanoampere per square centimeter without reducing the sensitivity of the detectors. The heterojunction perovskite films are formed by laminating several membrane films filled with perovskites of different bandgaps. A gradient bandgap is formed during annealing. The detectors have a lowest detectable dose rate of 13.8 ± 0.29 nGy air s −1 for 40-keV x-ray and can conduct dynamic x-ray imaging at a low-dose rate of 32.2 nGy air s −1 . Simulation and experimental analysis show that the heterojunction is tolerant of halide diffusion and can be stable for over 15 years.

Advances in Photoelectric Detection Units for Imaging Based on Perovskite Materials

“…a) Structure diagram of heterojunction perovskite membrane, b) J – V curves of single‐component and heterojunction perovskite devices, c) X‐ray response of single‐component and heterojunction perovskite PDUs, d) X‐ray images of “UNC” taken by heterojunction perovskite PDUs, e) X‐ray image of metal wrench in metal box by heterojunction perovskite PDUs; Reproduced with permission. [ 120 ] Copyright 2021, The Authors, some rights reserved, exclusive licensee American Association for the Advancement of Science. f) Device structure of bilayer perovskite X‐ray PDUs, g) cross‐section SEM of bilayer perovskite film, h) stability test of bilayer perovskite PDUs under different doses of X‐ray irradiation, i) digital photographs and X‐ray imaging images of printed circuit boards; Reproduced under the terms of the Creative Commons CC‐BY license.…”

“…Zhou et al significantly reduced the leakage current of the device by constructing polycrystalline perovskite heterojunction. [120] The nylon films immersed in Cs 0.15 FA 0.85 PbI 3 and Cs 0.15 FA 0.85 Pb(I 0.15 Br 0.85 ) 3 were imprinted together by high temperature calcination. Due to the different energy level structures of the two kinds of perovskites, the perovskite heterostructure was formed (Figure 15a).…”

“…Figure 15. a) Structure diagram of heterojunction perovskite membrane, b) J-V curves of single-component and heterojunction perovskite devices, c) X-ray response of single-component and heterojunction perovskite PDUs, d) X-ray images of "UNC" taken by heterojunction perovskite PDUs, e) X-ray image of metal wrench in metal box by heterojunction perovskite PDUs; Reproduced with permission [120]. Copyright 2021, The Authors, some rights reserved, exclusive licensee American Association for the Advancement of Science.…”

Vertical matrix perovskite X-ray detector for effective multi-energy discrimination

“…Recently lead halide perovskites are emerging as promising semiconductors for direct X-ray detection, with excellent properties of large X-ray stopping power, high sensitivity and low detection limit 14 – 16 . The X-ray detection sensitivity is on the order of 10 3 –10 5 μC Gy air −1 cm −2 13 , 17 .…”

High grain boundary recombination velocity in polycrystalline metal halide perovskites

“…Understanding carrier recombination behaviors in metal halide perovskite materials and devices is important for improving the performance of perovskite optoelectronic devices (1). Metal halide perovskites have achieved great progresses in photovoltaic application with rapid increase of the power conversion efficiency of perovskite solar cells from 3.8 to 25.5% (2)(3)(4) and other applications of radiation detectors (5,6), light detectors (7,8), and light-emitting diodes (9) with performance comparable to or better than existing technologies. While the bulk and surface recombination in perovskites have been widely studied, carrier recombination at the hidden grain boundaries (GBs) of polycrystalline perovskite films that are adopted in most of the state-of-the-art high-performance devices has not been well understood, leaving behind the ongoing debate of whether GBs are benign or detrimental to device performances (10).…”