By Ying Wang, Yunqi Liu,* Yabin Song, Shanghui Ye, Weiping Wu, Yunlong Guo, Chong-an Di, Yanming Sun, Gui Yu and Wenping Hu

Organic field-effect transistors (FETs), as the critical components of organic integrated circuits (ICs), have attracted considerable attention due to their low cost, easy processability, flexibility, and applicability to large-area devices. However, there are still many challenges, which can impede organic FETs from practical application in organic ICs. The major challenges remaining are the decrease of the pinch-off voltage (V_P) and precise control of the threshold voltage (V_T).

In this paper, OFETs with a poly(N-vinylcarbazole) (PVK) buffer layer between SiO₂ and organic semiconductors are fabricated. The PVK buffer layer not only improves the performance of the devices (the mobility up to 0.5 cm² V^-1s^-1) but also sharply reduces the absolute value of the pinch-off voltage at different V_GS down to lower than 20 V. More interestingly, the number of charges stored in PVK layer can be changed by the starting V_GS, resulting in the systematically control of threshold voltage in a single device.

Advanced Materials., （2008, 20(3), .611-615）

Figure 1. a) Molecular structure of PVK and the cross-sectional view of organic FETs. b) Output characteristic of pentacene FETs with PVK buffer layer. c) Output characteristic of pentacene FETs without a PVK buffer layer.