Ambipolar Transport in Phase-Separated Thin Films of p- and n-Type Vanadylporphyrazines with Two-Dimensional Percolation

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• 作者：Chihiro Nanjo ; Takuya Fujimoto ; Michio M. Matsushita ; Kunio Awaga
• 刊名：Journal of Physical Chemistry C
• 出版年：2014
• 出版时间：July 3, 2014
• 年：2014
• 卷：118
• 期：26
• 页码：14142-14149
• 全文大小：554K
• ISSN：1932-7455

文摘

Phase separation in thin films of organic p- and n-type semiconductors has attracted much attention for applications as bulk heterojunctions in organic photovoltaic devices and thin-film transistors (OTFTs). In the present study, we examined the structures, electronic states, and transistor performance of the codeposited thin films of p- and n-type porphyrazines, vanadylphthalocyanine (VOPc), and vanadyltetrakis(1,2,5-thiadiazole)porphyrazine with various mixing ratios. The transistors exhibited ambipolar performance, in which the p-type mobility increases with an increase in the VOPc ratio, and vice versa for the n-type mobility. This can be explained by a phase separation in these thin films. In addition, the mixing ratio dependence of the transistor parameters such as mobility and on/off ratio clearly indicated that the hole and electron carrier transports in the thin films are governed by the two-dimensional percolations of the p- and n-type semiconductor domains, respectively. We also fabricated electric-double-layer transistors of the codeposited thin films with ionic liquid gate dielectrics and found significant improvements in the mobility and threshold voltage and a high on/off ratio. The complementary inverters composed by these OTFTs worked in the first and third quadrants with a large signal gain over 10.