Thermochromism and X-ray detection capabilities of a hybrid double metal halide perovskite (C3H12N2)2AgBiBr8

Abstract

Two-dimensional (2D) layered hybrid double metal halide perovskites have recently gained significant attention as lead-free and environmentally benign alternatives to lead halide perovskites. In this study, we report the photophysical properties of a 2D Dion–Jacobson (DJ) type hybrid double perovskite, (C₃H₁₂N₂)₂AgBiBr₈, which exhibits both reversible thermochromism and promising X-ray radiation detection capabilities. This material shows transition from a low-temperature monoclinic P2₁/n phase to a high-temperature monoclinic C2/m phase at 121.83 °C along with a color change from yellow to bright orange. The phase transition is reversible and both single crystals and bulk powder samples of (C₃H₁₂N₂)₂AgBiBr₈ remain stable for more than 30 heating–cooling cycles. Optical property characterization shows that (C₃H₁₂N₂)₂AgBiBr₈ is a semiconductor with an indirect band gap of 2.42 eV. The material demonstrates a semiconductor resistivity of 2.8 × 10¹⁰ Ω cm, lower than those of other reported DJ-type hybrid double perovskites, and also shows response towards soft X-rays (8 keV) with a detector sensitivity of 188.52 μCGy⁻¹ cm⁻². These properties along with a very high signal-to-noise ratio (SNR) value (111.45) indicate the potential of (C₃H₁₂N₂)₂AgBiBr₈ for direct radiation detection.