A novel Ag-Bi-S-I chalco-halide nanomaterial for photovoltaic applications

Perovskite-like lead-free semiconductors are an emerging class of materials, primarily investigated for photovoltaic (PV) applications, as lead-based perovskites, despite their high efficiencies, suffer from toxicity and instability when exposed to oxygen and moisture. Among these materials, multi-anion structures known as chalco-halides (CH) are particularly promising due to optimal band gap values (~1.6 eV) and defect-tolerant structure, fundamental parameters for efficient light energy harvesting. Chalco-halide materials can be classified into several groups based on the type of metal cation: transition-metal CH, heavy pnictogen CH, mixed-metal CH, and organic-inorganic CH [1]. While many of these materials have been synthesized and tested in PV devices, others remain theoretically predicted. Here, we report the fabrication of Ag-Bi-S-I chalco-halide nanoparticles via a novel synthesis approach. Furthermore, synchrotron radiation X-ray aerosol photoelectron spectroscopy (XASP) was employed to investigate the valence and core level electronic structure. The results are compared with the results of the electronic structure of chalcogenide AgBiS2 and a previously reported halide Ag-Bi-I system [2].