(139g) Rebirth of Amine Thiol Chemistry: A Strategy for Moderate Temperature Processing of BaMS3 (M=Ti, Zr, Hf) Chalcogenide Perovskites

The semiconductor industry is experiencing remarkable growth and is anticipated to capture a trillion-dollar market share in the coming decade. However, the escalating demand and environmental concerns drive the necessity for the next generation of semiconductor materials to exhibit robust stability, natural abundance, eco-friendliness, and customizable properties to meet diverse applications, including transistors, photovoltaics, thermoelectrics, LEDs, and more. These advancements underscore the urgency to innovate novel materials to meet the escalating demand.

Chalcogenide perovskites is an emerging class of semiconductors with promising potential for photovoltaic applications. This encompasses a broad range of materials with a ABX₃ formula and a perovskite crystal structure, exemplified by BaZrS₃. These materials are anticipated to possess intriguing optoelectronic properties, such as customizable bandgap, high absorption coefficients, defect tolerance, and a high dielectric constant comparable to lead halide perovskites. Notably, chalcogenide perovskites offer stability, abundance in the Earth's crust, and non-toxicity similar to traditional chalcogenides like Cu(In,Ga)Se₂ and Cu₂ZnSnSe₄. However, despite their potential, chalcogenide perovskites have been hindered by their rudimentary synthesis procedures, often requiring temperatures as high as 800 - 1200°C for extended periods, thus limiting their practicality.

The primary challenges lie in the extreme oxophilicity of transition metals and the high stability of sulfide binaries and oxide ternaries, resulting in high-temperature synthesis and secondary oxide impurities. Therefore, in this study, we employ solution processing as a viable alternative for synthesizing chalcogenide perovskites, characterized by low-temperature and ambient-pressure processing, offering cost-effective investment and scalability opportunities.

We describe the utilization of reactive organometallic precursors in amine-thiol solution chemistry to establish a molecular precursor route for BaMS₃ (M=Zr, Hf, Ti) materials. The homogeneous barium and zirconium thiolate ink thus achieved was blade-coated and sulfurized to synthesize BaZrS₃ at a notable 575°C for 2 hours, in contrast to the higher temperatures traditionally reported. This methodology was successfully extended to other chalcogenide perovskite materials such as BaHfS₃ and related BaTiS₃. Subsequent material, morphological, and optoelectronic characterizations conducted on these films provided valuable insights for the device fabrication of these materials.