[18p-D102-1~23] 12.4 Organic light-emitting devices and organic transistors

[18p-D102-20] Controlling Turn-on Voltage of Organic Transistors by Introducing Gap States

〇Hiroyuki Matsui¹, Shizuo Tokito¹ (1.ROEL, Yamagata Univ.)

Keywords:organic field-effect transistors, OFETs, device simulation

In contrast to silicon MOSFETs which utilize impurity semiconductors as channels, organic field-effect transistors (OFETs) utilize intrinsic semiconductor in general. Then, the turn-on voltage V_ON of the OFETs is determined mainly by the gap states in the semiconductor channel and the difference of workfunctions between the channel and the gate electrode. So far, the gap states have been believed to degrade the OFET performances, and much effort have been made to reduce the gap states. This approach can improve the mobility and subthreshold slope SS, while it quite often makes the OFET normally-on, or depletion type, and causes a difficulty in the application to integrated circuits. In this study, we pursue the way to control the V_ON of OFETs by controlling the distribution of gap states but not just reducing them. For that purpose, the device simulations based on finite element method (FEM) and the experiments of introducing gap states by the co-evaporation of semiconductor molecule, DNTT (HOMO = -5.18 eV), and a small amout of donor molecule, DBTTF (HOMO = -4.70 eV).