Polymeric and Molecular Materials for Advanced Organic Electronics

Thin-film transistors (TFTs), both organic and hybrid, will be the enablers of next-generation flexible, possibly transparent, large-area, high-performance electronics for a myriad of civilian and defense applications. While progress has been made, current generation circuits, especially those deposited by solution processes, are limited by the paucity of high mobility () semiconductors (especially for electron transport), limited quality of compatible gate dielectrics, high power consumption, poor understanding of how critical materials interfaces affect carrier injection and transport, limited understanding of charge carrier dynamics and trapping mechanisms, and poor understanding of circuit radiation stability. In addition, current strategies for TFT integration and efficient printing, essential for organic complementary circuits are in an early stage of development. The objective of this collaborative program is to develop the understanding necessary to achieve high-performance polymeric and molecular materials enabling flexible high speed electronic circuits. To reach these goals the following project efforts are underway: 1) Design, synthesize, characterize high-mobility organic or hybrid semiconductors; ultimate target: m (solution grown films) ~ 40.0 cm2/Vs; m (printed) ~ 15 cm2/Vs in ambient; 2) Design, synthesize, characterize new gate dielectrics compatible with p-/n-type organic and inorganic semiconductors; 3) Characterize and elucidate nanoscale interfacial phenomena affecting TFT device charge injection, switching, and transport; 4) Fabricate pn junctions via bilayer or blending processes for diodes and ambipolar transistors and characterize their performance. 5) Understand materials properties by demonstrating several electronic building blocks by printing, including inverters, ring oscillators, rectifiers, D flip-flops. This proposal summarizes progress towards these goals and describes what we propose next in terms of elucidating fundamental material-property-device response, routes to unique molecular/-polymeric materials sets, and process/device platforms to advance the field of printed flexible electronics for the entire community.