Schematic illustration of various quasiparticle excitations in a model semiconducting polymer.
BACKGROUND: The majority of optoelectronic and charge/energy transport processes involve absorption and emission of light. Photoactive organic and hybrid organic-inorganic materials, including semiconducting polymers, covalent- and metal-organic frameworks, molecular aggregates and crystals, and layered perovskites display fascinating photophysical signatures and transport phenomena upon interaction with light. Excited state processes in commercially relevant materials are primarily governed by the quantum mechanical behavior of various mobile quasiparticles, such as excitons, polarons, bipolarons, trions, and other collective excitations. Unraveling excited-state phenomena and the underlying quantum mechanical factors that govern the photophysical response and charge/energy transport processes of quasiparticles in multifunctional materials necessitates a conceptual understanding of the intricate interplay among electronic coupling, vibronic coupling, electrostatic and inter-layer interactions, as well as different forms of structural and conformational disorder.
OVERVIEW: We strive to develop ab-initio parameterized coarse-grained model Hamiltonians that accurately describe the quantum mechanical behavior of quasiparticles in chemical and biophysical systems and focus on answering fundamental questions that reconcile conceptually complicated experimental observations and help accelerate materials discovery. Our research involves integrating physics-based model Hamiltonians with computer science techniques and computational chemistry approaches to investigate the electronic, optical, and transport properties of emergent organic and hybrid organic-inorganic semiconducting materials.
BROADER IMPACTS: Organic electronics research continues to find increasing commercial value with specific emphasis on developing environmentally sustainable and cost-effective semiconductors. The power conversion efficiency in organic solar cells is now up to 17% and a recent report by Emergen research projects the global organic electronics market to reach USD 178.5 billion by 2028. On the other hand, the field of layered perovskites has exploded in the last decade, and two-dimensional (2D) perovskites have emerged as promising candidates for next generation solar cells owing to record power conversion efficiencies. A fundamental understanding of how the combination of various quantum mechanical factors influence nanoscale energy and charge transport in organic and hybrid organic-inorganic materials serves as the foundation for the rational design of emergent semiconductor devices. The potential societal benefits of our proposed research include practical applications in photovoltaics, energy storage, field effect transistors, organic light emittiing diodes, and quantum computing.