Organic field-effect transistors with a sandwich structure from inserting 2,2′,2″-(1,3,5-benzenetriyl)tris[1-phenyl-1H-benzimidazole] in the pentacene active layer

¹ State Key Laboratory of Electronic Thin Films and Integrated Devices, School of Optoelectronic Information, University of Electronic Science and Technology of China (UESTC), Chengdu 610054, P.R. China
² Department of Electronic Engineering, College of Communication and Electronics, Chongqing University, Chongqing 400044, PR. China

^a e-mail: jsyu@uestc.edu.cn

Received: 5 July 2012
Revised: 20 January 2013
Accepted: 14 February 2013
Published online: 30 April 2013

Abstract

Organic field-effect transistors (OFETs) with a pentacene/TPBi/pentacene sandwich structure were realized and characterized. Compared with the single pentacene layer transistors, these devices not only showed an obvious reduction of threshold voltage but also presented a significant enhancement of field-effect mobilities. The performance improvement was attributed to the high conductivity of the sandwich active layers, which were analyzed by applying the transfer line method. Meanwhile, the morphologies of pentacene films with and without the TPBi interlayer were characterized by atomic force microscopy, the smoother surface of the upper pentacene film was observed in pentacene/TPBi/pentacene. Moreover, by applying X-ray diffraction, a higher-order growth phase of the pentacene thin film was observed.