Committee: 

Dr. Kippelen, Advisor  

Dr. Durgin, Chair

Dr. Reichmanis

Abstract:

The objective of the proposed research is to develop a universal approach to improve the operational and environmental stabilities of organic field-effect transistors (OFETs) using low-cost fabrication methods. A second goal is to develop organic photodetectors with high responsivity based on a novel device architecture with the highly-stable OFETs. The preliminary research shows a simple approach to balance the effects of two mechanisms causing shifts of the threshold voltage with opposite signs in long-term operation by engineering the bilayer gate dielectric comprising an amorphous fluoropolymer (CYTOP) layer and an Al2O3- HfO2 nanolaminate grown by atomic layer deposition (ALD) technique. This compensation mechanism leads to devices with remarkable thermal, environmental, and long-term operational stability that is comparable or superior to that of commercial inorganic TFT technologies. These OFETs with outstanding stability show great potential in a variety of applications, especially in light signal detection. Therefore, a new concept of organic photodetector based on these OFETs was demonstrated. The novel organic photodetector consists of a dual-gate OFET and an organic photodiode (OPD) that operates in a photovoltaic mode without power consumption. The advantages of fast photoresponse of OPD and amplification property of OFET enable a high photoresponsivity as well as short response time for this novel organic photodetector.