Fabrication, modelling and characterization of green light photosensitive p-channel -Poly[2,5-bis(3-tetradecylthiophen-2-yl)thieno[3,2-b]thiophene] organic semiconductor based phototransistors

Abstract

Solution processable poly[2,5-bis(3-tetradecylthiophen-2-yl)thieno[3,2-b]thiophene] (PBTTT- C14) organic polymer-light based field effect transistor (O-L-FET) has been developed for low-cost and large-area electronics applications. We have fabricated and studied the electrical as well as the optical performance of a p-channel PBTTT-C14 organic polymer-based thin film transistor under dark and steady-state illumination. Also, a model has been developed for understanding the device physics particularly, focusing on the impact of illumination on polymer/dielectric and metal-polymer interface. It has been intended to investigate the effect of green light on organic thin film transistor. An enhancement in the photogenerated charge carrier in the organic channel under green light (550 nm) illumination was observed, which is attributed to the absorption of photons and photogeneration of excitons followed by their diffusion and dissociation. A comprehensive study on PBTTT-C14 channel has been carried out by thorough optoelectronic characterization of the device. Also, the impact of illumination on the apparent threshold voltage shift from 11.83 V to 8.68 V has been explained on the basis of the mechanism of operation of the device under illumination. © 2019