Dr Suad Saeed Alghamdi

We report the development of a high sensitivity H2S gas sensor based on perovskite nanoparticles, which can be synthesized using relatively simple solution-growth methods. The gas sensor was fabricated from the metal halide perovskite formamidinium lead bromide (FAPbBr3), which exhibits a high sensitivity to H2S gas in the form of changes to the electrical conductivity. The response of the sensor to H2S gas showed a high sensitivity to gas concentrations in the range 0.5 – 100 ppm, with a fast response time of less than one minute under ambient room conditions.

We have investigated the performance of formamidinium lead bromide (FAPbBr3) perovskite X-ray detectors fabricated from polycrystalline material that is pressed into a pellet at high pressures. FAPbBr3 has been shown to exhibit a remarkable combination of electrical and physical properties, such that mechanically-formed polycrystalline pellets exhibit good charge transport properties suitable for use as X-ray detectors. We characterise the morphology and structure of FAPbBr3 pellets using photoluminescence (PL), electron microscopy (SEM) and X-ray diffraction (XRD), and demonstrate an improvement in the microstructure, density, and charge transport performance of the material as the pressure is increased from 12 MPa to 124 MPa. The use of annealing of the pellets after pressing also improves the stability and charge transport performance of the devices. Using a 40 kV X-ray beam, a maximum X-ray sensitivity of 169 µC Gy−1 cm−2 was measured, and the fast time response of the devices was demonstrated using a chopped X-ray beam.

Organic–inorganic hybrid metal-halide perovskites have emerged as potential semiconductors for high-performance X-ray detection owing to their large radiation stopping power, high sensitivity, large mobility-lifetime (μτ) product, and facile fabrication strategies. In recent times, two-dimensional (2D) layered perovskite-based X-ray detectors have attracted significant attention owing to their superior ambient and thermal stability, reduced ion migration, and low defect density. Notably, in 2D perovskites, the larger organic amine spacer integrated alternately between inorganic lead halide octahedral layers can effectively restrict ion migration even for higher bias voltages in X-ray detection. In this work, we have fabricated centimeter-sized high-quality butyl amine organic spacer-incorporated n = 1 layered Ruddlesden–Popper (RP) phase (BA)2PbI4 2D perovskite single crystals using a conventional slow cooling method and demonstrated their X-ray detection and imaging applications. The (BA)2PbI4 single crystal detector exhibits an excellent X-ray performance with a sensitivity of 148 μCGy–1 cm–2 at 10 V mm–1 applied electric field, an ultralow detection limit less than 241 nGy s–1, a very low and stable dark current (20.52 pA), and a quick response time of ∼4 ms. Moreover, the fabricated devices have shown remarkably stable responses for continuous X-ray exposure over 60 min and ultrahigh storage stability of over 4 months, confirming the material robustness and stability. Finally, high-resolution X-ray imaging is demonstrated using these (BA)2PbI4 single crystal-based detectors. The exceptional operational stability and high performance of (BA)2PbI4 X-ray detectors make them promising candidates for low-dose X-ray detection and imaging applications.