Improved Room Temperature NO2 Sensing Performance of Organic Field-Effect Transistor by Directly Blending a Hole-Transporting/Electron-Blocking Polymer into the Active Layer

Shijiao Han; Zuchong Yang; Zongkang Li; Xinming Zhuang; Deji Akinwande; Junsheng Yu

doi:10.1021/acsami.8b07838

Improved Room Temperature NO₂ Sensing Performance of Organic Field-Effect Transistor by Directly Blending a Hole-Transporting/Electron-Blocking Polymer into the Active Layer

ACS Appl Mater Interfaces. 2018 Nov 7;10(44):38280-38286. doi: 10.1021/acsami.8b07838. Epub 2018 Oct 26.

Authors

Shijiao Han^{1

2}, Zuchong Yang¹, Zongkang Li¹, Xinming Zhuang¹, Deji Akinwande², Junsheng Yu¹

Affiliations

¹ State Key Laboratory of Electronic Thin Films and Integrated Devices, School of Optoelectronic Science and Engineering , University of Electronic Science and Technology of China (UESTC) , Chengdu 610054 , P. R. China.
² Microelectronics Research Center , The University of Texas at Austin , Austin , 78758 Texas , United States.

PMID: 30360043
DOI: 10.1021/acsami.8b07838

Abstract

Over the past decades, organic field-effect transistor (OFET) gas sensors have maintained a rapid development. However, the majority of OFET gas sensors show insufficient detection capability towards oxidizing gases such as nitrogen oxide, compared with the inorganic counterpart. In this paper, a new strategy of OFET nitrogen dioxide (NO₂) gas sensor, consisting of poly(3-hexylthiophene-2,5-diyl) (P3HT) and poly(9-vinylcarbazole) (PVK) blend, is reported. Depending on the gate voltage, this sensor can operate in two modes at room temperature. Of the two modes exposed to NO₂ for 5 min, when the gate voltage is 0 V, the highest NO₂ responsivity of this OFET is >20 000% for 30 ppm (≈700% for 600 ppb) with the 1:1 P3HT/PVK blend, it is ≈40 times greater than that with the pure P3HT. The limit of detection of ≈300 ppb is achieved, and there is still room for improvement. While in the condition of -40 V, the response increases by 15 times than that with the pure P3HT. This is the first attempt to improve the OFET sensing performance using PVK, which usually functions as a hole-transport layer in the light- emitting device. The enhancement of sensing performance is attributed to the aggregation-controlling and hole-transporting/electron-blocking effect of PVK. This work demonstrates that the hole-transport material can be applied to improve the NO₂ sensor with simple solution process, which expands the material choice of OFET gas sensors.

Keywords: NO2 gas sensor; gate control; organic field-effect transistor (OFET); poly(3-hexylthiophene) (P3HT); poly(9-vinylcarbazole) (PVK); polymer blend; room temperature.