Molecular-Wire Energy Transfer and Exciton Diffusion in Self-Assembled Photonic Materials

Bowling Green State University, Bowling Green OH

Investigators

Abstract

Technical: The goal of this project is greater fundamental understanding of synthesis/processing and relationships between structure and photonic properties of self-assembled organometallic materials that allow for observation of both singlet and triplet excitons. The approach involves synthesis and investigation of coordination materials consisting of a singlet donor, with extended conjugated oligomers, and triplet acceptors, such as Pt(II) porphyrins. Two types of emissive coordination materials will be synthesized. One type will comprise two singlet state emitters, bis(8- quinolinolate)(AcAc)AlIII and conjugated oligomers, and doped-blended triplet acceptor, while the second will be composed of the same building block with the acceptor incorporated in a 'photonic wire' bridge. Studies will be focused on understanding the optical and structural properties of these materials. Particular attention will be devoted to the role of energy transfer and triplet diffusion. High-triplet energy components will be used to make materials capable of harnessing higher-energy processes for sky-blue and green phosphorescence. Insight into balancing sky-blue (~490 nm), green and orange/red emission and exciton-balance optimization via triplet-triplet energy transfer is expected to aid in the design of materials suitable for OLEDs and particularly for OLED-based solid-state lighting. The materials will be designed to allow for rigorous investigation of exciton dynamics, both singlet and triplet as well as exciton diffusion, processes of high importance in many solid state devices. Depending on the material components and method of excitation/sensitization, three processes, singlet, triplet energy transfer, and exciton diffusion proceed on different timescales, allowing evaluation of the processes separately. Non-technical: The project addresses basic research issues in a topical area of materials science with technological relevance in electronics and photonics. This project is aimed at investigating energy transfer and exciton diffusion processes that have a major impact on performance of organic electronic materials. The knowledge generated during the work on this project will enable a better understanding and design of materials that will be used in OLEDs, organic photovoltaics, thus contributing to the development of energy-efficient technologies. The project emphasizes integrated education and research in training of pre-college, undergraduate, and graduate students through laboratory participation, complementary coursework, and outreach activities. The multidisciplinary character of the project provides a unique opportunity for education of undergraduate and graduate students and postdocs. This is also a goal of the associated state-funded Building Ohio Talent for a Sustainable Energy Future program aimed at STEM areas of renewable energy generation for Ohio undergraduates in chemistry and physics. This program also enables community college students to transfer to Bowling Green St. U. and receive B.S. education in STEM majors.