Solution-grown BiI/BiI3 van der Waals heterostructures for sensitive X-ray detection

Abstract

X-ray detectors must be operated at minimal doses to reduce radiation health risks during X-ray security examination or medical inspection, therefore requiring high sensitivity and low detection limits. Although organolead trihalide perovskites have rapidly emerged as promising candidates for X-ray detection due to their low cost and remarkable performance, these materials threaten the safety of the human body and environment due to the presence of lead. Here we present the realization of highly sensitive X-ray detectors based on an environmentally friendly solution-grown thick BiI/BiI3/BiI (BixIy) van der Waals heterostructure. The devices exhibit anisotropic X-ray detection response with a sensitivity up to 4.3 × 104 μC Gy−1 cm−2 and a detection limit as low as 34 nGy s−1. At the same time, our BixIy detectors demonstrate high environmental and hard radiation stabilities. Our work motivates the search for new van der Waals heterostructure classes to realize high-performance X-ray detectors and other optoelectronic devices without employing toxic elements.

Alternating BiI3–BiI van der Waals Photodetector with Low Dark Current and High-Performance Photodetection

“…Through X-ray photoelectron spectroscopy (XPS), ultraviolet photoelectron spectroscopy (UPS), and UV–Vis–NIR (NIR = near-infrared) diffuse reflectance spectroscopy (DRS), the elemental compositions of the high-order heterostructure have been further determined, and the energy band structure can be revealed, as shown in Figures S4 & S5. Similar results have also been exhibited in our previous article . Based on the characterizations above, the BiI 3 –BiI sample has a dual bandgap at ∼1.68 and 0.72 eV, respectively, and the band diagram of the BiI 3 –BiI heterostructure can be provided, as shown in Figure b.…”

“…Similar results have also been exhibited in our previous article. 29 Based on the characterizations above, the BiI 3 −BiI sample has a dual bandgap at ∼1.68 and 0.72 eV, respectively, and the band diagram of the BiI 3 −BiI heterostructure can be provided, as shown in Figure 1b. BiI 3 and BiI form the type II alignment, and the in-built electrical field is constructed at their interface by diffusing electrons from BiI 3 to BiI.…”

“…Recently, we have successfully synthesized a kind of van der Waals heterocrystal by a low-temperature solution refinement technique, where thick bismuth­(III)-iodide (BiI 3 ) layers (main) are alternately stacked with thin Bi-rich layers (minor) with a chemical formula of BiI . Other than the previously layer-by-layer restacking or CVD epitaxy, the high-quality binary heterostructure nanosheets can be directly exfoliated from the BiI 3 –BiI heterocrystal.…”

“…Recently, we have successfully synthesized a kind of van der Waals heterocrystal by a low-temperature solution refinement technique, where thick bismuth(III)-iodide (BiI 3 ) layers (main) are alternately stacked with thin Bi-rich layers (minor) with a chemical formula of BiI. 29 Other than the previously layer-by-layer restacking or CVD epitaxy, the highquality binary heterostructure nanosheets can be directly exfoliated from the BiI 3 −BiI heterocrystal. In addition, since BiI 3 is a 2D layered semiconductor with a moderate energy bandgap (∼1.7 eV) and high absorption coefficient (>10 5 cm −1 at visible wavelengths), 30−32 the BiI 3 −BiI heterostructure has promising potential as alternative photoactive material for photodetection and other optoelectronic applications.…”

Aminoazanium of A-site Cations in Metal-Free Halide Perovskite Single Crystals to Reduce Thermal Expansion for Efficient X-ray Detection

“…1−3 Meanwhile, the concept of green electronics manufacturing has also been respected, that is, the use of environmentally friendly new materials and new technologies to reduce the impact of electronic products on the environment, reduce energy loss, and other issues. 4,5 However, the mature commercial X-ray detection materials, including silicon (Si), amorphous selenium (α-Se), and cadmium zinc telluride (CZT), are more or less characterized by high-temperature preparation, toxicity, and high cost, which is contrary to the concept of green environmental protection. 6,7 Although the burgeoning metal halide perovskites (MHPs) have outstanding advantages such as cheap, low-temperature deposition and solvent-processability, they inevitably use toxic metal ions or organic solvents.…”