Collaborative Research: Harnessing entropy to discover new chalcogenide semiconductors

NON-TECHNICAL DESCRIPTION New solid-state materials are essential to advance existing or create new technologies. Materials synthesis remains a crucial bottleneck to the materials discovery process. This project directly addresses this synthesis bottleneck in an emerging class of ternary chalcogenide-based semiconductors. Many materials in this family have been computationally predicted to have excellent properties for solar cells, energy-efficient electronics, and batteries – materials needed to directly and indirectly advance national health and security. However, experimental synthesis of these predicted materials has proven challenging, as only a handful of these materials have been made. This project involves computationally-led experiments and experimentally-informed computational work to understand and design new synthetic approaches to access these materials. The collaborative nature of this project provides a unique training experience for graduate students through their engagement in advanced computational and experimental research. TECHNICAL DESCRIPTION This project aims to discover new ternary chalcogenides for optoelectronic applications by leveraging alternative entropy sources that can enable materials synthesis. Many ternary chalcogenides have been predicted to be thermodynamically stable and exhibit compelling optical or electronic properties. Yet, only a small fraction of these predicted compounds have been experimentally synthesized. This project operates under the hypothesis that synthesis of these materials requires careful control of thermodynamic driving forces through entropic factors to prevent competitive compositional decomposition reactions or polymorphic transitions. Specifically, this project employs control over entropy associated with point defect formation, crystal vibrations, and gas evolution to stabilize and synthesize targeted chalcogenide materials relative to competing binary reaction products or polymorphs. The synthesis science discoveries have potential to apply broadly to other classes of materials. This collaborative project leverages first-principles thermodynamic calculations to lead experimental synthesis and characterization, as well as experimental work to inform computational efforts. Together, this project provides comprehensive training to student researchers in solid-state materials chemistry. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.