Design and Preparation of Organic-Metal Halide Hybrids Exhibiting Charge Transfer

University Of Southern California, Los Angeles CA

Investigators

Abstract

PART 1: NON-TECHNICAL SUMMARY In the last ten years, solar cells based on hybrid materials that contain organic and inorganic components have exhibited rapidly improving performance that has now reached levels competitive with commercial silicon panels. Through this project, which is supported by the Solid State and Materials Chemistry program at NSF, the research team at the University of Southern California develops a deeper understanding of why these materials perform so exceptionally well and investigates strategies to push the performance of these hybrid materials even higher in the future. The work is highly interdisciplinary, combining efforts in organic synthesis, computational chemistry, and physical property measurements to examine how light interacts with these complex materials. The project also engages undergraduates from the nearby Cerritos Community College (which is 54% Latino, 8% African American) and Native American High School students in the research. PART 2: TECHNICAL SUMMARY This project, which is supported by the Solid State and Materials Chemistry program at NSF, deepens our fundamental understanding of how organic molecules in their excited state interact within periodic inorganic structures. In previous studies the organic component has been predominantly structural in nature, not actively participating in the valence or conduction bands. In this project the research team at the University of Southern California focuses on materials where the organic component is an active optical or electronic element, by making it a major contributor to the valance and/or conduction bands of the hybrid solid. The principle investigators develop new material design principles to promote enhanced charge transport of photoexcited carriers through the solid state. In the process, new understanding is achieved about how to align the highest occupied (HOMO) and lowest unoccupied molecular orbitals (LUMO) of organic dyes with the conduction or valence bands of the extended framework. The materials that are developed during this study act as model systems to investigate how localized excitons on the organic molecules can be transferred into the far more delocalized bands of the metal halide region of the crystal. The systematic investigation involves a combination of materials design, synthesis, Density Functional Theory calculations, and physical property measurement to answer fundamental questions about how the organic and inorganic components interact within the crystal structure. Additionally, the project engages undergraduates from the nearby Cerritos Community College (which is 54% Latino, 8% African American) and Native American High School students in the research. 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.