Influence of bottom electrode configuration on crystalline structures of 6,13-bis(triisopropylsilylethynyl) pentacene films for all-inkjet-printed organic thin film transistors

The paper aims to investigate the influence of bottom electrode configurations in all-inkjet-printed organic thin film transistors (OTFTs) on crystalline structures of semiconductor layers as well as the electrical performance of OTFTs. Two different types of all-inkjet-printed OTFTs were fabricated: one type with a new bottom-top contact configuration and the other type with a conventional bottom-bottom contact configuration. The crystal growth of semiconductor layer and the electrical characteristics of OTFTs were evaluated and compared between two different bottom electrode configurations. The resulting crystalline structures of semiconductor layers are mostly affected by the evaporation process of semiconductor layer. Randomly-oriented crystalline structures are generated in the semiconductor layer with a conventional bottom-bottom contact configuration due to irregular evaporation. However, a new bottom-top contact configuration leads to well-oriented crystalline structures because of controlled contact line movement. The average mobility of OTFTs with well-oriented crystalline structures is about 11 times as high as that with randomly-oriented crystalline structures.