SusChEM: Designing Small-Molecule Replacements for Fullerenes in Organic Photovoltaics

University Of Washington, Seattle WA

Investigators

Abstract

Principal Investigator: Samson Jenekhe Number: 1435912 Nontechnical Description The sun represents the most abundant potential source of pollution-free energy on earth. Solar cells for conversion of light to electricity based on organic polymers integrated into a photovoltaic (PV) device offer a potentially low-cost route for renewable electricity production. The proposed research will enable the development of a new generation of low-cost solar cells based on organic materials. Specifically, this project will design and synthesize of a novel class of organic materials with electronic properties that seek to replace expensive fullerene materials used as the electron acceptor component of organic polymer based solar cells. The new materials, and solar cells made from them, have the potential to be more durable, inexpensive, and manufacturable at a large scale compared to current materials for organic polymer based solar cells. With respect to education and broadening participation, the project will provide for the training of graduate and undergraduate students in chemistry, chemical engineering, nanotechnology, and materials science and engineering. The project will enable the principal investigator to continue a longstanding history of facilitating the involvement of undergraduate, women, and minority students in research. Technical Description This project will study a novel class of organic materials with electronic properties that seek to replace expensive fullerene materials used as the electron acceptor component of organic polymer based photovoltaic devices (OPVs). Fullerene derivatives, particularly [6,6]-phenyl-C61-butyric acid methyl esters (PCBMs), have traditionally dominated fundamental studies of the photophysics, carrier dynamics, blend morphology, and charge transport/extraction for OPV materials. This project seeks to determine if non-fullerene small-molecule or discrete oligomer electron acceptor materials such as tetraazadifluoranthrene diimide can be rationally designed and experimentally realized with charge photogeneration and photovoltaic properties that are superior to fullerene-PCBMs. The project will focus on new n-type organic semiconductors based on a three-dimensional non-planar oligomer motif. The intrinsic electron transport and charge photogeneration properties of the new n-type oligomers will be investigated, and OPV devices incorporating the new acceptor oligomers with test donor polymers will be fabricated and characterized with respect to their morphology, photovoltaic performance, and charge transport properties. The observed structure-property-performance relationships of the n-oligomer/p-polymer OPV systems will be used to validate the rational molecular design approach. The difference in molecular geometry of the proposed n-type oligomers (3D non-planar and non-spherical) relative to the well-studied fullerenes is expected to result in new material morphologies that may lead to improved photoconversion in n-oligomer/p-polymer blends, and thus advance fundamental understanding of charge separation, transport, and collection in OPV devices. With respect to education and broadening participation, the project will provide for the training of graduate and undergraduate students in chemistry, chemical engineering, nanotechnology, and materials science and engineering. The project will enable the principal investigator to continue a longstanding history of facilitating the involvement of undergraduate, women, and minority students in research.