Self‐Powered FA 0.55 MA 0.45 PbI 3 Single‐Crystal Perovskite X‐Ray Detectors with High Sensitivity

Despite the rapid progress of hybrid organic-inorganic halide perovskites in optoelectronic applications, their water resistance is still limited because of the interaction of both the organic and inorganic components with water molecules. In this study, a cation engineering protocol to obtain a material with inherent high water resistance by incorporating benzamidinium (BAH) cations into the bismuth halide framework is developed. Analysis of the crystal structure indicates that (BAH)BiI 4 exhibits a molecular 1D perovskitoid structure with an edge-sharing mode and strong noncovalent interactions within the crystal, including I•••I interaction, hydrogen bonding, and π-π stacking between adjacent BAH cations. Such strong noncovalent interactions provide excellent water resistance, with negligible decomposition of crystals during water soaking for two months. The feasibility of the (BAH)BiI 4 crystal for X-ray detection, with a sensitivity as high as 1181.8 µC Gy air −1 cm −2 and a detection limit below 77 nGy air s −1 under 50 V bias is further demonstrated. Such good values are due mainly to efficient charge transport along the π-π stacking between neighboring BAH cations and I•••I interactions between adjacent inorganic chains. These findings provide a new approach to improve the water resistance of perovskite/perovskitoid optoelectronic devices.

Section: Application Of X-ray Detectionmentioning

confidence: 99%

Water‐Resistant Lead‐Free Perovskitoid Single Crystal for Efficient X‐Ray Detection

Chen

et al. 2022

“…[8] In Pbbased perovskite single crystals, charge transport properties are superior to α-Se; moreover, energy-resolving capability has been shown in various device configurations made from singlecrystal perovskites. [14,[21][22][23][24][25][26][27][28] Hence, perovskite detectors with low leakage current toward next-generation X-ray detection, are anticipated to be better suited for photon-counting-based applications.…”

Section: Introductionmentioning

confidence: 99%

Sensitivity and Detection Limit of Spectroscopic‐Grade Perovskite CsPbBr₃ Crystal for Hard X‐Ray Detection

Hadar

Siena

et al. 2022

Spectroscopic‐grade single crystal detectors can register the energies of individual X‐ray interactions enabling photon‐counting systems with superior resolution over traditional photoconductive X‐ray detection systems. Current technical challenges have limited the preparation of perovskite semiconductors for energy‐discrimination X‐ray photon‐counting detection. Here, this work reports the deployment of a spectroscopic‐grade CsPbBr3 Schottky detector under reverse bias for continuum hard X‐ray detection in both the photocurrent and spectroscopic schemes. High surface barriers of ≈1 eV are formed by depositing solid bismuth and gold contacts. The spectroscopic response under a hard X‐ray source is assessed in resolving the characteristic X‐ray peak. The methodology in enhancing X‐ray sensitivity by controlling the X‐ray energies and flux, and voltage, is described. The X‐ray sensitivity varies between a few tens to over 8000 μC Gyair−1 cm−2. The detectable dose rate of the CsPbBr3 detectors is as low as 0.02 nGyair s−1 in the energy discrimination configuration. Finally, the unbiased CsPbBr3 device forms a spontaneous contact potential difference of about 0.7 V enabling high quality of the CsPbBr3 single crystals to operate in “passive” self‐powered X‐ray detection mode and the X‐ray sensitivity is estimated as 14 μC Gyair−1 cm−2. The great potential of spectroscopic‐grade CsPbBr3 devices for X‐ray photon‐counting systems is anticipated in this work.

“…X-ray detectors in the direct-conversion mode have been widely applied in medical diagnosis, security screening, computed tomography imaging, nondestructive determination, container inspection, etc. [1][2][3][4][5][6][7][8] The properties of X-ray detectors are largely determined by the semiconductors that translate the X-rays into an electrical signal. Metal-halide perovskite single crystals (PSCs) have been found to be promising candidates for making high-performance X-ray detectors at low cost due to their large atomic number Z (X-ray attenuation coefficient α∝Z 4 ), high mobility-lifetime product μτ (to ensure effective carrier collection), tunable bandgap (1.5-2.5 eV, to control thermal noise), low trap density (to improve μτ value), large resistance (to reduce the dark current), and low-temperature solution synthesis (for cost reduction).…”

Section: Introductionmentioning

confidence: 99%

First‐Principles Calculation Design for 2D Perovskite to Suppress Ion Migration for High‐Performance X‐ray Detection

Zhang

et al. 2021

Ion migration is a key root-cause of photocurrent instability in perovskite X-ray detectors. Although 2D perovskite single crystal (PSC) is a good candidate to suppress ion migration compared with its 3D counterpart, its intrinsic stability still needs to be improved. In this work, it is first envisioned to conquer the ion migration by enhanced chemical bonding; the proposal is further confirmed by density functional theory calculations, in which the bonds are made stronger by introducing a fluorine atom into the ortho position of phenethylamine (o-F-PEA) to shorten the distance between adjacent organic cations in the crystal lattice for enhanced electrostatic interactions between the F atom and the neighboring benzene ring. It is further demonstrated experimentally that the activation energy for ion migration (AEIM) of (o-F-PEA) 2 PbI 4 PSC is increased compared with that of (PEA) 2 PbI 4 PSC. The improved AEIM is also confirmed by enhanced thermal stability. Consequently, the dark current in the (o-F-PEA) 2 PbI 4 2D PSC X-ray detectors is reduced by two times compared with the (PEA) 2 PbI 4 reference. Furthermore, the detector shows the sensitivity of 1724.5 μC Gy air −1 cm −2 at 1250 V mm −1 , and much improved photocurrent stability.