Solution-Grown Formamidinium Hybrid Perovskite (FAPbBr₃) Single Crystals for α-Particle and γ-Ray Detection at Room Temperature

Abstract

Compared with the widely reported MAPbBr 3 single crystals, formamidinium-based (FA-based) hybrid perovskites FAPbBr 3 (FPB) with superior chemical and structure stability are expected to be more efficient and perform as more reliable radiation detectors at room temperature. Here, we employ an improved inverse temperature crystallization method to grow FPB bulk single crystals, where issues associated with the retrograde solubility behavior are resolved. A crystal growth phase diagram has been proposed, and accordingly, growth parameters are optimized to avoid the formation of NH 4 Pb 2 Br 5 secondary phase. The resulting FPB crystals exhibit a high resistivity of 2.8 × 10 9 Ω•cm and high electron and hole mobility−lifetime products (μτ) of 8.0 × 10 −4 and 1.1 × 10 −3 cm 2 •V −1 , respectively. Simultaneously, the electron and hole mobilities (μ) are evaluated to be 22.2 and 66.1 cm 2 •V −1 •s −1 , respectively, based on the time-of-flight technique. Furthermore, a Au/FPB SC/Au detector is constructed that demonstrates a resolvable gamma peak from 59.5 keV 241 Am γ-rays at room temperature for the first time. An energy resolution of 40.1% is obtained at 30 V by collecting the hole signals. These results demonstrate the great potential of FAPbBr 3 as a hybrid material for γ-ray spectroscopy and imaging.

A Tunable Electrochemical Strategy toward an All-Inorganic CsPbBr3 Perovskite

“…33 This process has significantly shown that the formation of NH 4 Pb 2 Br 5 is actually a reversible reaction and that NH 4 Pb 2 Br 5 can be applied as an effective precursor for the formation of CsPbBr 3 , although it had normally been considered as an impurity that deteriorates the perovskite formation in previous research. 30,31 To ensure complete conversion of NH 4 Pb 2 Br 5 to perovskite and optimize the film morphology, the CsPbBr 3 perovskites in this work were all obtained by spin-coating a CsBr methanol solution 8 times on the NH 4 Pb 2 Br 5 substrates. In order to study the changes in the electronic structure and chemical states of the samples before and after the application of CsBr, X-ray photoelectron spectroscopy (XPS) measurements were performed on the samples at different stages during the fabrication, as shown in Figure 4b−d.…”

Self-Powered X-ray Detection and Imaging using Cs2AgBiCl6 Lead-Free Double Perovskite Single Crystal

“…X-ray detection and imaging have been used extensively in various applications such as medical diagnostics, nondestructive inspection, security screening, and scientific research. − Although conventional semiconductors, for example, cadmium telluride (CdTe), amorphous selenium (α-Se), and silicon (Si), have been applied extensively as X-ray detectors, they suffer from small Z (atomic number), insufficient mobility lifetime (μτ), and high processing cost. − To satisfy the requirement of high sensitivity for direct X-ray detectors, it is critical to prepare superior semiconductor materials at a reasonable cost. Recently, lead-halide perovskite single crystals (SCs) with large atomic numbers and high μτ products have been considered as a strong candidate for X-ray detectors with high performance at a lower cost. − Although lead halide perovskites have made significant progress, − their practical applicability is still limited due to the usage of potentially toxic lead and inherent ion migration properties leading to baseline drift and deteriorated image resolution. ,, Metallic lead (Pb) can cause serious neurological and nephrological problems. , Therefore, it is imperative to find Pb-free solution-processed perovskite SCs to meet the demands of high-performance X-ray detectors with good imaging capability.…”

High Yield Solution Growth of FACsPbBr3 Single Crystals with Low Defect Density for Gamma-ray Spectroscopy

“…FA0.9Cs0.1PbBr3 detector also can clearly resolve 241 Am spectrum with a resolution of 9.8±0.4 % at 59.5 keV (Fig. S5a), which is four times better than previously reported results of FAPbBr3 single crystals 31 . FA0.9Cs0.1PbBr3 detectors showed a great linear response in the studied energy range from 59.5 to 662 keV.…”

“…Since FA0.9Cs0.1PbBr3 devices can detect α-particle generated by 241 Am decay with an energy resolution of 17.5±0.9% (Fig. S5b), we also extracted peak positions of 5.5 MeV radiation from voltage-dependent spectrums and fitted them by Hecht equation 31,34 . The µhτh and µeτe are 2.9×10 -3 cm 2 V -1 and 1.8 ×10 -3 cm 2 V -1 , respectively, as shown in Fig.…”