CAREER: First-Principles Investigation of Energy Transport Within Ordered Organic Assemblies

Trustees Of Boston University, Boston

Investigators

Abstract

NONTECHNICAL SUMMARY This CAREER award supports computational research and education focused on understanding the interaction of light with ordered assemblies of carbon-based organic molecules, with the goal of realizing advanced solar energy conversion materials. Solar energy conversion refers to the process of harnessing light from the sun and converting it to electricity or chemical energy; this is a promising technology for addressing the challenges associated with the projected future growth in energy needs. This technology requires new materials, designed specifically to achieve more efficient and inexpensive solar energy conversion devices. In contrast to the traditional inorganic materials used in solar energy conversion devices, organic materials are abundant, and their properties can be extensively tuned using techniques of synthetic organic chemistry. The PI will utilize advanced computer simulation techniques to investigate how electrons within organic assemblies respond to light and develop physically intuitive models of the influence of molecular structure on electronic properties. The goal of this research is to use computer simulation to discover new rules to design organic assemblies that can convert solar energy efficiently. This project will integrate education and outreach with research through numerous channels. The PI will incorporate simulation methods developed in this research project into the graduate level course "Computational Materials Science". In collaboration with the Boston University Technology Innovation Scholars Program, where undergraduate students interested in becoming teachers will contribute to teaching at diverse high schools throughout the Boston area, lesson plans will be developed that incorporate the applicability of the research to solar energy conversion. Together with the research team, the PI will participate in the Boston University U-Design program, introducing middle school age kids to computational science by means of design projects. In collaboration with the BU Outreach and Diversity Program, the research team will deploy activity kits to museums across the world, introducing the scientific concepts to the broader community. TECHNICAL SUMMARY This CAREER award supports computational research and education aimed at developing a physically intuitive understanding of optical excitations and energy transfer within organic assemblies. Organic materials are a highly tunable class of optically active materials that are promising for photovoltaics and artificial photosynthesis. The field of organic chemistry can synthesize molecular assemblies with a great degree of precision; however, understanding needed to design these systems for efficient energy transfer is lacking. Theory and computation will be used to develop a deeper physical intuition about the excited-states of organic materials. This project focuses on the role of long-range order on the optical properties of organic molecules in the condensed phase. The PI and research team will employ first-principles electronic structure theory to better understand how optically excited states within ordered organic assemblies can be controlled to deliver improved photovoltaic and photocatalytic efficiency. The determination of structure-property relationships is critical for the design of new molecules; the PI and her research team will quantify aspects of the optically excited state, such as the interaction of excitons with phonons, which significantly impacts energy transfer and conversion but is challenging to understand and quantify. Furthermore, these studies will shed light on the behavior of electron-hole pairs in systems where excitonic effects are strong. Additionally, new computational methodology will be developed for probing the role of electron-phonon interactions, which are very difficult to characterize in extended systems. Feedback from experimental collaborators aiming to validate the predictions will be used to improve the computational approach, and thereby increasing the impact of this research. The ultimate result of this research will be to provide new design rules to enable the development of organic materials that can efficiently direct optical excitations along molecular assemblies. This project will integrate education and outreach with research through numerous channels. The PI will incorporate simulation methods developed in this research project into the graduate level course "Computational Materials Science". In collaboration with the Boston University Technology Innovation Scholars Program, where undergraduate students interested in becoming teachers will contribute to teaching at diverse high schools throughout the Boston area, lesson plans will be developed that incorporate the applicability of the research to solar energy conversion. Together with the research team, the PI will participate in the Boston University U-Design program, introducing middle school age kids to computational science by means of design projects. In collaboration with the BU Outreach and Diversity Program, the research team will deploy activity kits to museums across the world, introducing the scientific concepts to the broader community. 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.