Rational Design of High-performance Semiconductors based on Inorganic Perovskites Containing Bismuth

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NON-TECHNICAL DESCRIPTION: The development of high-performance oxide semiconductors with desired electronic structure has direct implications on many energy-related applications including photovoltaics, high-power electronics, and photocatalysis. This project employs an integrated theoretical and experimental approach to rapidly discover new high-performance semiconductors based on perovskite-framework oxides and oxynitrides containing bismuth. This family of promising compounds represents a vast composition space that remains largely unexplored. The project combines first-principles quantum-mechanical calculations with materials informatics to rapidly predict promising new semiconductors. Advanced synthesis and characterization techniques are used to optimize the microstructure and improve the performance of these semiconductors. Education and outreach components of the project focus on preparing both graduate and undergraduate students for the workforce needed to realize advanced energy technologies. The project leverages a co-advised doctoral program, the McDonnell Academy Global Energy and Environmental Partnership (MAGEEP), to provide graduate students with an international experience to interact with their counterparts from universities in developing countries, where energy issues play a vital role. TECHNICAL DETAILS: The project seeks to discover high-performance and defect-tolerant semiconductors that can replace unstable and toxic lead-halide perovskites in a variety of applications including in high-efficiency solar cells and photocatalysis. This is carried out by replacing the toxic lead cation in 2+ oxidation state with isoelectronic bismuth cation in 3+ oxidation state, without compromising the advantages presented by the perovskite framework. This interdisciplinary research combines first-principles density-functional theory calculations with materials informatics to accelerate the discovery of stable Bi-based perovskites with targeted band gap and electronic structure. The research employs a combination of solid-state chemistry, wet-chemistry and aerosol-based synthesis techniques to synthesize the predicted materials and control their microstructure. It uses a variety of characterization techniques including aberration-corrected scanning transmission electron microscope imaging and monochromated electron energy loss spectroscopy for atomic-scale characterization of the defects in the synthesized materials. Education aspects include training of undergraduate and graduate students including exposure to international students working on energy materials and the organization of summer workshops on nanomaterials for energy applications for K-12 teachers and students from schools in St. Louis and the surrounding region.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.