Conjugated Polyelectrolytes for Optoelectronic Applications

University Of California-Santa Barbara, Santa Barbara CA

Investigators

Abstract

Technical Summary This proposal concerns the synthesis and properties of conjugated polyelectrolytes. These materials are described by a polymer backbone with a p-delocalized electronic structure and pendant groups with functionalities capable of ionizing in a high dielectric medium. Very recently, applications of conjugated polyelectrolytes in the fabrication of optoelectronic devices have shown that they can make a substantial impact in emerging technologies based on organic semiconducting materials. The major goal of the proposal is thus to develop an understanding of their bulk thermal and optoelectronic properties by designing specific molecular structures that address properties of interest. Novel synthetic methods will be developed to increase the structural diversity of conjugated polyelectrolytes by introduction of new repeat units, pendant groups and choice of counterions. Differential scanning calorimetry will be used to correlate molecular structure to thermal properties, such as melting and glass transition temperatures, which bear relevance to device stabilities. Nanoscale electronic properties, as a function of molecular structure and processing methods, will be examined by using various atomic force microscopy techniques. Charge injection at interfaces and charge mobility in the bulk will be assessed by four probe measurements of films and by the fabrication of field effect transistors. Completion of the work will fill large gaps in our understanding of conjugated polymer properties and how these impact function in applications such as electrochemiluminescent cells, organic light emitting diodes, thin film transistors and solar cells. Additionally, conjugated polyelectrolytes have found widespread utility in biological and chemical sensory schemes that offer advantages over small molecule-based alternatives. Non-Technical Summary Conjugated polyelectrolytes are a class of organic semiconductors that enable better performance of emerging organic-based technologies such as multicolor displays, less energy intensive illumination sources, efficient solar cells, highly sensitive biological detection systems and printable electronics. The work in this proposal will yield a better understanding of how to optimize device function and manufacturing options by controlling and designing the relevant properties at the molecular level. The work described is highly interdisciplinary and provides an excellent medium for educating the next generation of scientists interested in bridging traditionally non-overlapping areas of science and technology. Focused studies can be carved out from the proposed work suitable for the schedules of undergraduate students, high school teachers and community college instructors. Previous research in conjugated polyelectrolytes has yielded considerable valuable intellectual property, which has led to the creation of several start up companies.