CAREER: Advanced Devices and Testing using Organic Field Effect Transistors

Columbia University, New York NY

Investigators

Abstract

This project will develop two new device systems which take advantage of the processing characteristics of organic field effect transistors (OFETs); a programmable logic cell (an organic PAL, a building block for creating an organic FPGA) and a piezoelectric film coupled OFET amplifier. The project will also investigate the interplay between the processing technologies used to fabricate and tune organic field effect transistors (OFETs) and circuit-level performance. This effort will develop a new tool to directly measure trap states in OFET devices to more thoroughly characterize that interplay. The proposed project will answer several long standing questions about the influence of processing techniques on shallow and deep trap states in these devices, spatially map both the trap density and electrically active grain distribution in OFETS, and lead to a deeper understanding of the role of processing and interfaces in OFETs. The fabrication and device platform and the tools developed for it will be integrated into both a capstone laboratory-based undergraduate course and modules for an outreach program which reaches underrepresented groups in the Harlem neighborhood of Manhattan. Intellectual merit OFETs are used in a number of applications where their relatively straightforward fabrication, inherent mechanical flexibility, and low temperature processes are of benefit. This project will develop two new device architectures that take advantage of the low processing temperature and flexibility of OFETs to create a programmable logic cell and a piezoelectric sensor. Most examination of pentacene-based OFETs has focused on measurements that examine aggregate properties (such as I-V characteristics) and often make assumptions inconsistent with trap-limited conduction. By using appropriate models and resolving both excitation and measurement in time, location, and energy, it will be possible to probe a variety of phenomena which are otherwise invisible. Of greatest interest are the effects of processing in a large-area compatible fashion. The tools developed will also be able to probe the internal states of the programmable logic cell and piezoelectric device fabricated in this program. Broader impact This program will have significant impact beyond its immediate scientific and engineering output. A number of student populations will be engaged by this project including a high school student recruited through the NYAS SRTP program each summer, one undergraduate student each year, and one doctoral student per year. These students will contribute to the national supply of highly qualified personnel in this field. An additional outreach component will be through Columbia's GK12/TIP program administered through the School of Engineering and Applied Science. Two student years of outreach will be delivered by a second graduate student on the project who will work with high school teachers in Harlem to develop and deliver teaching modules based on this work. This outreach will have a significant impact on a traditionally underrepresented student population. The device platforms developed will be integrated with the PI's previous work to create a new capstone undergraduate laboratory course at Columbia University on advanced display devices. Results from the research and educational components of the program will be disseminated through the literature and conferences in this field to other researchers and the public at large. On a societal scale, the development of OFET technology has tremendous potential. Wide availability of systems based on these devices could revolutionize the delivery of healthcare, IT, banking, commerce, and security, bringing significant benefits to both our society and the global community.