Band Gap Tuning in Inorganic Chlorine-Based Halide Perovskites Via Solid-State Synthesis at Room Temperature

Abstract

Inorganic chlorine-based halide perovskites have emerged as promising materials in optoelectronics and photovoltaics due to their high electron mobility and tunable optical properties. However, traditional solution-based synthesis methods for these perovskites face significant challenges, such as poor solubility, environmental sensitivity, and scalability issues. This paper introduces an energy-efficient, environmentally friendly approach using ball-milling for room-temperature solid-state synthesis of inorganic chlorine-based halide perovskites with variable band gaps, including CsCdCl₃ (4.72 eV) and mixed chlorine systems CsPbBr₂Cl (2.58 eV) and CsPbCl₂Br (2.40 eV). This solid-state method not only effectively overcomes the limitations of solution-based synthesis, including the need for toxic solvents and significant environmental impact, but also enables precise band gap tuning and yields materials with excellent phase control, high purity, and stability. The stability of the resulting materials was evaluated by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), UV-Vis, and photoluminescence (PL). The results show remarkable stability for up to 90 days when stored in air at room temperature. Utilizing the room-temperature solid-state approach to synthesize chlorine-based halide perovskites not only overcomes the limitations of traditional methods but also paves the way for the development of advanced optoelectronic devices.