(385z) The Promise and Challenges of Chalcogenide Perovskites

Solar energy is growing at an unprecedented rate and in a historic milestone in 2022, the installed PV capacity surpassed all other forms of energy. Though the current photovoltaic market is dominated by silicon technology, the search for other novel materials is still on the rise. Researchers are looking for materials that can achieve higher efficiency and provide unique capabilities such as flexibility and aesthetics, while being nontoxic and environmentally friendly.

One such material that has garnered the research community’s attention is chalcogenide perovskites. Chalcogenide perovskites are materials with the chemical formula ABX₃ and a perovskite crystal structure. A well-known example is BaZrS₃. Chalcogenide Perovskites are known for their stability and more importantly abundance in nature, and non-toxicity, which are essential for the next generation of photovoltaic materials. They have also shown promising optoelectronic properties. For instance, this polycrystalline material has the highest reported absorption coefficient (~10^{^5} cm^-1) which can translate to ultra-thin flexible solar cells with absorber thickness of just around 200nm. Despite such potential, the rudimentary synthesis methodologies of these materials have hindered commercialization. Traditional synthesis methodologies have been limited to high temperatures of 800 to 1200℃ and extending periods from hours to days.

My work introduces a novel strategy utilizing amine thiol chemistry and organometallic precursors to develop a fully solution processed route for BaMS₃ (M=Zr, Hf, Ti) chalcogenide perovskites. Ba and Zr precursors were successfully dissolved in a ink, blade coated and sulfurized to synthesize BaZrS₃ at remarkable 575⁰C and 2hr in contrast to the higher temperatures reported traditionally. This approach was further extended to BaHfS₃, BaTiS₃ and other related materials. Comprehensive material, morphological, and optoelectronic characterizations conducted on these films, provide valuable insights into the chalcogenide perovskite family and represent a key step towards device fabrication.

Research Interests

Process development, solution chemistry, thin film fabrication, material, morphological, and optoelectronic characterizations