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Effect of Vertical Annealing on the Nitrogen Dioxide Response of Organic Thin Film Transistors
Sihui Hou1, Xinming Zhuang2, Zuchong Yang3
1State 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, China. 201621050313@std.uestc.edu.cn.
Abstract:
Nitrogen dioxide (NO₂) sensors based on organic thin-film transistors (OTFTs) were fabricated by conventional annealing (horizontal) and vertical annealing processes of organic semiconductor (OSC) films. The NO₂ responsivity of OTFTs to 15 ppm of NO₂ is 1408% under conditions of vertical annealing and only 72% when conventional annealing is applied. Moreover, gas sensors obtained by vertical annealing achieve a high sensing performance of 589% already at 1 ppm of NO₂, while showing a preferential response to NO₂ compared with SO₂, NH₃, CO, and H₂S. To analyze the mechanism of performance improvement of OTFT gas sensors, the morphologies of 6,13-bis(triisopropylsilylethynyl)-pentacene (TIPS-pentacene) films were characterized by atomic force microscopy (AFM) in tapping mode. The results show that, in well-aligned TIPS-pentacene films, a large number of effective grain boundaries inside the conducting channel contribute to the enhancement of NO₂ gas sensing performance.
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