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Nano Research

Article Title

Organic-semiconductor: Polymer-electret blends for high-performance transistors

Authors

Peng Wei, Frontier Institute of Science and Technology, and State Key Laboratory of Electrical Insulation and Power Equipment, Xi’an Jiaotong University, Xi’an 710054, China
Shengtao Li, Frontier Institute of Science and Technology, and State Key Laboratory of Electrical Insulation and Power Equipment, Xi’an Jiaotong University, Xi’an 710054, China
Dongfan Li, Frontier Institute of Science and Technology, and State Key Laboratory of Electrical Insulation and Power Equipment, Xi’an Jiaotong University, Xi’an 710054, China
Han Yu, Frontier Institute of Science and Technology, and State Key Laboratory of Electrical Insulation and Power Equipment, Xi’an Jiaotong University, Xi’an 710054, China
Xudong Wang, Frontier Institute of Science and Technology, and State Key Laboratory of Electrical Insulation and Power Equipment, Xi’an Jiaotong University, Xi’an 710054, China
Congcong Xu, Frontier Institute of Science and Technology, and State Key Laboratory of Electrical Insulation and Power Equipment, Xi’an Jiaotong University, Xi’an 710054, China
Yaodong Yang, Frontier Institute of Science and Technology, and State Key Laboratory of Electrical Insulation and Power Equipment, Xi’an Jiaotong University, Xi’an 710054, China
Laju Bu, School of Science, Xi’an Jiaotong University, Xi’an 710049, China
Guanghao Lu, Frontier Institute of Science and Technology, and State Key Laboratory of Electrical Insulation and Power Equipment, Xi’an Jiaotong University, Xi’an 710054, China

Keywords

organic field-effect transistors, organic electronics, vertical phase separation, gate stress, polymer electrets, C12-BTBT

Abstract

ABSTRACT As compared with polymer semiconductors, solution-processed small-molecule semiconductors usually have poorer film-formation properties, which induces wide variations in device performance in terms of mobility and threshold voltage, thus severely limiting their commercial applications. In this work, we propose an easily accessible method to improve the performance and reduce the variability of small-molecule organic field-effect transistors (OFETs) by blending organic semiconductors with an insulator polymer, which is subsequently post-treated by gate stress to generate an electret. By blending the organic semiconductor 2,7-didodecyl[1]benzothieno[3,2-b][1]benzothiophene (C12-BTBT) with the insulator polystyrene, uniform transport layers with vertically phase segregated morphology are obtained, from which the mobility and threshold voltage of OFETs are largely manipulated. The OFETs exhibit field-effect mobilities as high as 7.5 cm2·V−1·s−1 with an on/off ratio exceeding 106 in ambient conditions. This double-layer structure provides an appropriate architecture for applying gate-stress to inject charges into the insulating layer, forming an electret. The generation of the electret is thermally accelerated and thus can be easily realized under moderate gate-stress at elevated temperature (e.g., 60 °C). After cooling, the electret layer serves as a floating-gate, which not only continuously tunes the threshold voltage and field-effect mobility, but also helps minimize the contact resistances and optimize the subthreshold swing. As an application of this method, a digital inverter is built and its performance is optimized via in situ tuning of its individual transistors.

Graphical Abstract

Publisher

Tsinghua University Press

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