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CAER Seminars

ORGANIC ELECTRONICS: TRANSISTORS,DIODES AND PHOTOVOLTAICS

Speaker:
Dr. John Anthony
UK Dept. of Chemistry
University of Kentucky

Date:
Friday, June 11, 2004, 3:30pm
Ben Bandy Conference Room
UK Center for Applied Energy Research

Abstract: Our group takes a molecular engineering approach to the synthesis of fucntionalized acene-based materials for use in a variety of electronic applications. Our main focus is on increasing the stability and solubility of acenes, while simultaneously improving their electronic properties through careful engineering of their solid-state order. Functionalized pentacenes have been prepared that are significantly more stable than the parent compound, and have solubilities greater than 100 mg / mL in chloroform. Because the compounds are engineered to have strong pi-face interactions in the solid state, they form highly crystalline films with ease and form solution-cast field-effect transistor devices with mobilities in excess of 0.2 cm2 / Vs. Further functionalization of these derivatives leads to new materials with even more promising properties.

For OLEDs, we have shown that the best performance is derived from materials engineered to possess no aryl-aryl close contacts in the solid state. In such molecules, materials that form highly crystalline films exhibit better performance than similar materials that form amorphous films. The ease of functionalization of these acenes has allowed us to apply our molecular engineering approach to the preparation of blue, green, and most recently, highly efficient red-emitting materials.

Our photovoltaic research involves the preparation of p-type and n-type pentacene derivatives. Through application of our models for pentacene derivative crystallization, we have been able to design such materials to have nearly identical lattice parameters, and thus they are more likely to form an excellent heterojunction interface. We are also working on extending the absorption window of acene materials, through the preparation of stable materials based on heptacene.