Investigation of the atmosphere influence on device characteristics and NO2 sensing performance of organic field-effect transistors consisting of polymer bulk heterojunction

• Published in: Organic electronics Vol. 62; pp. 114 - 120
• Main Authors: Yang, Zuchong, Han, Shijiao, Liu, Yufan, Zhuang, Xinming, Akinwande, Deji, Yu, Junsheng
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.11.2018
• Subjects: Atmosphere influence; Bulk heterojunction; Nitrogen dioxide sensor; Organic field-effect transistor (OFET); Semiconducting polymer; Nitrogen dioxide sensor; Atmosphere influence; Semiconducting polymer; Organic field-effect transistor (OFET); Bulk heterojunction
• ISSN: 1566-1199; 1878-5530
• DOI: 10.1016/j.orgel.2018.07.023

Organic field-effect transistors (OFETs) using polymer as the active layer are being intensively developed for flexible electronics including gas sensor. The strategy of polymer blends comprising semiconducting polymer mixed into an insulating polymer matrix has shown great potential in improving the electrical and sensing performance of OFETs. Herein two semiconducting polymers of poly(3-hexylthiophene-2,5-diyl) (P3HT) and poly(9-vinylcarbazole) (PVK) are used to construct a polymer bulk heterojunction, through exploring the atmosphere influence on device characteristics and NO2 sensing performance of the transistors, an in-depth illumination of the underlying sensing mechanism is carried out. Firstly, by using nitrogen (N2) and dry air as carrier gases, the individual device characteristics and sensing performance under certain NO2 concentrations are investigated. It can be observed that O2 has a greater effect on the electrical performance than other atmospheric components, which is different from the previous report of neat P3HT-based device. Specifically, at the high gate voltage, the response of drain current under N2 is more than 2 times higher than that under dry air, and the mobility variation exhibits a 2-fold enhancement. In contrast, at a low gate voltage (0 V) under dry air, the response is 2-fold greater than under N2. Then, the underlying sensing mechanism of these gas sensors consisting of various P3HT fractions in different operating environment is discussed. Finally, the OFET gas sensor with a high sensitivity to NO2 under dry air is obtained, i.e., the highest current sensitivity is ∼12381% for 15 ppm with 50% P3HT, which is more than 30 times higher than that of pure one. This study on gas sensing mechanism of OFET consisting of semiconducting polymer bulk heterojunction can offer novel inspiration to realize high performance OFET and the corresponding gas sensor. [Display omitted] •Solution processed OFET consisting of polymer bulk heterojunction is fabricated.•NO2 gas sensor based on OFET can be operated at room temperature.•NO2 responses vary distinctly under different carrier gases.•Underlying mechanism is attributed to adsorbed oxygen and depletion layer.•A high detection level of NO2 in terms of sensitivity is realized.