Oriented 2D Perovskite Wafers for Anisotropic X‐ray Detection through a Fast Tableting Strategy

Abstract

2D perovskite single crystals have emerged as excellent optoelectronic materials owing to their unique anisotropic properties. However, growing large 2D perovskite single crystals remains challenging and time‐consuming. Here, a new composition of lead‐free 2D perovskite—4‐fluorophenethylammonium bismuth iodide [(F‐PEA)3BiI6] is reported. An oriented bulk 2D wafer with a large area of 1.33 cm2 is obtained by tableting disordered 2D perovskite powders, resulting in anisotropic resistivities of 5 × 1010 and 2 × 1011 Ω cm in the lateral and vertical directions, respectively. Trivalent Bi3+ ions are employed to achieve a stronger ionic bonding energy with I‐ ions, which intrinsically suppress the ion‐migration effect. Thus, the oriented wafer presents good capabilities in both charge collection and ion‐migration suppression under a large applied bias along the out‐of‐plane direction, making it suitable for low‐dosage X‐ray detection. The large‐area wafer shows a sensitive response to hard X‐rays operated at a tube voltage of 120 kVp with the lowest detectable dose rate of 30 nGy s‐1. Thus, the fast tableting process is a facile and effective strategy to synthesize large‐area, oriented 2D wafers, showing excellent X‐ray detection performance and operational stability that are comparable to those of 2D perovskite single crystals.

Spray-coated perovskite hemispherical photodetector featuring narrow-band and wide-angle imaging

“…Quasi-two-dimensional (quasi-2D) perovskites are solution-processable and combine the advantages of excellent charges carriers’ dynamics behavior of 3D perovskite and good stability of 2D perovskite 22 – 26 . Their unique optoelectronic properties of anisotropic quantum confinement, tunable bandgap, and defect tolerance nature enable attracting applications in photovoltaic 27 , 28 , light-emitting diode (LED) 29 , 30 , laser 31 , X-ray detectors 32 – 35 , and photodetectors 4 . Spray-coated perovskite films for solar cells have been reported for large area devices 36 , 37 .…”

How the Microstructure of MAPbI3 Powder Impacts Pressure-Induced Compaction and Optoelectronic Thick-Film Properties

“…In recent years, the application of halide perovskite thin films in solar cells with amazingly fast increasing power conversion efficiencies has attracted much attention in the field of optoelectronics . Moreover, other halide perovskite-based applications such as LEDs as well as photo- and X-ray detectors were also demonstrated. − In the case of perovskite X-ray detectors, especially single-crystal-based devices showed remarkably high sensitivities. , However, as the integration of perovskite single crystals in industry-relevant length scales and geometries remains challenging, perovskite powder-based thick films represent an attractive alternative for a versatile realization of perovskite X-ray detectors. − …”

Anisotropy in Perovskite Single Crystals: From Fundamentals to Applications

“…112 Moreover, Li et al demonstrated the anisotropic X-ray detection in 2D perovskite 4-fluorophenethylammonium bismuth iodide [(F-PEA) 3 BiI 6 ] wafers. 113 The resistivity of this wafer was found as 5 × 10 10 Ω cm in the lateral direction and 2 × 10 11 Ω cm in the vertical direction, which shows the anisotropic carrier transport in this material. In the lateral direction, the μτ product was estimated as 4 × 10 −4 cm 2 V −1 , which is significantly higher than the vertical direction ( 8 10 −5 cm 2 V −1 ) because the continuous bismuth halide octahedral sheets provide a smooth charge carrier transport in the vertical direction.…”

“…Moreover, Li et al. demonstrated the anisotropic X-ray detection in 2D perovskite 4-fluorophenethylammonium bismuth iodide [(F-PEA) 3 BiI 6 ] wafers . The resistivity of this wafer was found as 5 × 10 10 Ω cm in the lateral direction and 2 × 10 11 Ω cm in the vertical direction, which shows the anisotropic carrier transport in this material.…”