Investigating the doping effect of molybdenum oxide on a p-type organic thin-film transistor and their application to unipolar circuits

Abstract

This study focuses on investigating the doping effect of molybdenum oxide (MoOX) on a p-type organic dinaphtho[2,3-b:2′,3′-f]thieno[3,2-b]thiophene (DNTT) thin-film transistor (TFT) and its implications for various electronic applications. Specifically, we examined the influence of the doping position of MoOX on the transistor performance. When MoOX was doped between the electrode and the semiconductor (ME-OTFT), it facilitated charge injection by reducing the surface roughness. Consequently, the on-current and mobility of the ME-OTFT slightly increased compared to the undoped device. Additionally, when MoOX was fully covered on the ME-OTFT (MF-OTFT), it caused hole accumulation at the interface between DNTT and MoOX, forming a top channel. As a result, the off-current significantly increased, leading to an on-off ratio of 8.74 A/A, indicating the operation in depletion mode. Furthermore, we successfully demonstrated p-type unipolar inverters using the MF-OTFT as a pull-down device and the DNTT TFT as a pull-up device. Specifically, we implemented a zero-VGS connection inverter and a diode connection inverter with a maximum voltage gain of 22.06 V/V. The findings contribute to a deeper understanding of the effects of MoOX doping and its potential for enhancing device performance in unipolar circuits applications. © 2023 Elsevier B.V.