Charge Carrier Space-Charge Dynamics in Complex Materials for Solar Energy Conversion: Multiscale Computation and Simulation

Charge Carrier Space-Charge Dynamics and Reactivity in Photo-electro-chemical Interfaces: Multiscale Computation and Simulation Michel Dupuis, University at Buffalo (Principal Investigator) The research deals with timely societal challenges in renewable energy, and efficient and cost-effective conversion of solar energy to electrical and chemical energies. Current conversion efficiencies, including for solar water splitting into dihydrogen and dioxygen, are far from what they need to be for practical applications. Our long-term vision is to solve key science challenges in photo-electro-chemical conversion systems by means of computation and simulation, to contribute to the design of systems with superior performance. The challenges are in light absorption and charge carrier generation, charge carrier transport, and charge carrier reactivity. The present project has two thrusts: one deals with modeling of the transport of photo-generated electron and hole charge carriers in complex crystalline materials for solar energy conversion, combining first principles atomistic and mesoscale simulations. The combined modeling is indispensable forqualitativeandquantitativeunderstanding of how carrier transport affects conversion efficiency. We aim to establish a theoretical foundation for facet selectivity and homo-junctions, two emerging strategies toward enhanced charge separation and conversion performance. A second thrust deals with the characterization of interfacial redox chemistry in tailored oxygen-deficient interfaces for enhanced activity. We carry also timely studies of excitons – excited states precursors to charge carriers - for detailed experiment/theory validation based on emerging experimental data. The objectives, approach, and outcomes are within the realm of two fundamental research themes emphasized by the DOE/BES Division of Chemical Sciences, Geosciences, & Biosciences, namely “Charge Transport and Reactivity” and “Chemistry at Complex Interfaces”. The research addresses how the flow of charge carriers in complex crystalline environments of single phase, multi-phase, and multi-materials semiconductor systems can be tailored to enhance redox reactivity for photo-electro-chemical conversion. The research is aligned also with the national “Materials Genome” strategic initiative, through the development of validated software tools to accelerate design and discovery. Through our collaborations, students participating in this research are immersed in collaborative international research and cultural experiences.