CAREER: Theoretical Investigation of Photo-induced Charge and Energy Transfer in Organic Photovoltaic Materials

Cornell University, Ithaca NY

Investigators

Abstract

Nandini Ananth of Cornell University is supported by a CAREER award from the Chemical Theory, Models and Computational Methods program in the Chemistry Division to develop new theoretical methods to uncover a detailed, atomistic-level picture of the factors that drive efficient electron and energy transport in material systems. A delicate balance of chemical interactions along with external forces like light and heat determine the outcomes of reactions in complex molecular systems. The current research focuses on designing organic solar cell materials that absorb solar photons and efficiently generate free electrons. The long-term objectives of this research are to develop a complete toolbox of theoretical methods that can provide general, transferable design principles for materials relevant to renewable energy technology. The use of mathematical tools to understand chemical reactions is central to the proposed work, and is reflected in the educational outreach component of this award. The early incorporation of mathematics significantly impacts aptitude for science in the later stages of education and is an important step towards encouraging participation in Science, Technology, Engineering and Mathematics (STEM) careers. This challenge is addressed by working with high-need school districts to develop lesson plans and demonstrations that encourage the gradual incorporation of mathematical tools in science classrooms. The technical challenges addressed in this work include accurately modeling the electronic structure of large, many-atom systems and developing a computationally efficient method to incorporate quantum dynamic effects in condensed-phase charge and energy transfer processes. The electronic structure challenge is addressed with fragment-based methods where a large system calculation is divided into many accurate calculations on smaller subsystems using a high level of theory. The challenge of dynamics is to develop a method that can accurately capture quantum effects, but that is based on classical molecular dynamics where the computational effort scales well with system size. Here, this is achieved by mapping the quantum dynamics of a complex system to the classical dynamics of an isomorphic classical system derived using the path-integral representation of quantum mechanics. The methods developed here are general, and allow accurate studies of quantum behavior in complex systems with applications to many areas beyond condensed-phase photochemistry. The group works with schools in New York State, and in particular the high-needs focus district of Syracuse City, to develop curricular materials that incorporate math and that meet the new Next Generation Science Standards adopted by the state.