Effect of interface-dependent crystalline boundary on sub-threshold characteristics in a solution-processed 6,13-bis(triisopropylsilylethynyl)-pentacene thin-film transistor

School of Electronics Engineering, Kyungpook National University, Daegu 702-701, Republic of Korea

^a e-mail: jhbae@ee.knu.ac.kr

Received: 9 September 2013
Revised: 13 January 2014
Accepted: 11 February 2014
Published online: 24 March 2014

Abstract

We demonstrate how the sub-threshold characteristics are affected by the density of crystalline domain boundaries directly governed by an organic semiconductor (OSC) – a gate insulator interface in a solution-processed 6,13-bis(triisopropylsilylethynyl)-pentacene (TIPS-pentacene) thin-film transistor (TFT). For generation of an engineered interface, a self assembled monolayer of octadecyltricholorosilane (OTS) was produced between a solution processed TIPS-pentacene film and a silicon dioxide layer. The interfacial charge trap density (N_trap) deduced from the sub-threshold characteristics was significantly minimized after OTS treatment due to reduced crystal domain boundaries in the TIPS-pentacene film. In addition, the carrier mobility exhibits a value twice as large by OTS treatment. It is found that less crystal domain boundaries in the solution-processed OSC obtained from the engineered interface play an important role in inducing improved sub-threshold characteristics together with increased carrier mobility in organic TFTs.