ERI: Theory and Simulation of Photoexcitation Dynamics in 2-Dimensional Materials for Solar Energy Harvesting

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This award is funded in whole or in part under the American Rescue Plan Act of 2021 (Public Law 117-2).Meeting the increasing energy demands of the world’s growing population in environmentally sustainable ways is among the most important scientific challenges facing society today. One such approach is to tap into the energy from sunlight; however, current materials used to capture solar energy are costly to manufacture and relatively inefficient. To contribute to efficient harvesting of solar light for energy conversion processes, this project is designed to determine how specific properties of two types of 2-dimensional materials enable absorption of solar energy. State-of-the-art computational approaches are used to model these energy conversion processes at the level of atoms and their electrons. The project integrates the knowledge of material science, engineering, and computational physical chemistry. The results of this research will improve our understanding of materials currently under experimental investigation for use of solar energy harvesting devices and provide insights to improve their efficiency. Dr. Trivedi’s research program is integrated with an educational component to inspire undergraduate and graduate students to pursue careers in science, technology, and engineering.Two dimensional nanoporous materials displays a rich array of photophysical properties that govern excitation dynamics within the material resulting in efficient charge and energy generation and transport. However, fundamental questions have emerged from recent experiments regarding the influence of interface, defects, and dopants on the charge and energy dynamics of planar nanoporous materials and their power conversion efficiencies used in solar energy harvesting devices. Specifically, how exciton quenching and undesired charge trapping contribute to these events is uncertain. This project will investigate nonequilibrium processes involved in exciton generation and transport, and in charge separation following photoexcitation in two specific types of nanostructures: (i) Cu3HHTT2 MOF as a representative of a family of 2D - conjugated MOFs with honeycomb-like sheet structures and (ii) monolayer of tri-s-triazine-based graphitic carbon nitride. Using a combination of mixed quantum-classical approaches and nonadiabatic molecular dynamics this computational research will provide a detailed, atomistic level description of the photoexcitation dynamics. The investigation of influence of dimensionality, interfaces, defects, and dopants on the material’s light harvesting performance will be understood by pursuing two objectives, to (i) elucidate the influence of interface on charge and energy transfer using electronic structure theory and (ii) investigate nonequilibrium phenomena involved in exciton generation and transport followed by charge separation at the interface. Computational determination of the charge and energy dynamics within and at interfaces of these planar nanoscale materials will provide essential insights for their optimal use in devices for solar energy harvesting, sensing, imaging and other advanced technologies.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.