CAREER: Smart Molecular Design for One-Dimensional n-Type Nanostructures: Controlling Electronic Properties and Morphologies

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TECHNICAL SUMMARY: Well-defined nanostructures of organic semiconductors are important not only for future nanoelectronics, but also for improving the performance of current organic optoelectronic devices. There are two critical issues in modern organic optoelectronics: the scarcity of useful n-type semiconductors and poor charge transport in solution-processed films. This proposal presents a novel approach for addressing these two critical issues using one molecular design procedure.Creating one-dimensional (1D) nanostructures via intermolecular ð-orbital overlap is a promising approach for achieving enhanced charge mobility. With the guidelines obtained from the PI?s previous experiments in generating 1D nanostructures from certain asymmetrically substituted electron-deficient bisphenazines, three types of novel 1D n-type nanomaterials are proposed: i) T-shaped heteroaromatic building blocks with controllable electronic properties and self-assembly morphologies using peripheral substituents, ii) dimers and trimers of the T-building blocks connected through ð-conjugation, and iii) dimers and trimers of the T-building blocks connected with electron-withdrawing partners. The main objectives of this research are to develop a fundamental understanding of the structure-property relationship in terms of the tunability of the electron-deficiency, and to enhance the controllability of the 1D nanostructure morphologies derived from the new n-type materials.Organic photovoltaic devices will be fabricated using the n-type nanomaterials as a constituent of the heterojunction, providing a large donor/acceptor interface area for exciton dissociation and enhanced charge transport through the pathway created by the nanostructures. The proposed work covers both fundamental aspects as well as device applications. The feedback from device performance will guide future upgrades in the materials? design.NON-TECHNICAL SUMMARY: It is necessary to utilize vast solar sources to overcome energy challenges of tomorrow. Organic solar cells can provide light-weight, flexible, and cheaper devices. However, an obstacle to improve device performance is lack of one of the crucial components (n-type semiconductors). The purpose of this project is to develop novel organic nanomaterials for organic solar cells (and other electronic devices) to overcome this obstacle through novel molecular designs, and thus help making organic solar cells play a significant role in the future energy portfolio.This project includes an outstanding opportunity for educational outreach involving a local high school. The PI is in a unique position to utilize his research for motivating young students in their early education with eye-catching visualization and real research experiences. Throughout the project period, the PI will initiate a partnership with local high schools in the Clark County School District, launching a summer high school student internship and a high school teacher summer research program. In addition, the combination of synthetic chemistry, molecular assembly, nanoscience, organic materials, and optoelectronic device application will provide an excellent intellectual stage for graduate and undergraduate students to learn about interfacial chemistry which has growing importance as a contemporary science.