Significant improvement of 2,9-DPh-DNTT organic thin-film transistors based on organic heterojunction buffer layer

Abstract

High-mobility thin film transistors of para-sexiphenyl (p-6P)/2,9-diphenyl-dinaphtho[2,3-b:2′,3′-f]-thieno[3,2-b] thiophene (2,9-DPh-DNTT) are demonstrated by employing copper hexadecafluorophthalocyanine (F16CuPc), cobalt (II) hexadecafluoro-phthalocyanine (F16CoPc) and molybdenum oxide (MoO3) as buffer layers. The highest field-effect mobility of 9.3 cm2/Vs is achieved by using the F16CoPc buffer layer, which is the highest reported mobility for polycrystalline 2,9-DPh-DNTT thin film transistors. The improvement of the device performance is due to reducing device contact resistance between metal electrodes and the organic semiconductor and improving the carrier injection. Based on the optimized results, we fabricated an OTFT array consisting of p-6P/2,9-DPh-DNTT OTFTs with F16CoPc as the buffer layer by photolithography. A high mobility of 2.7 cm2/Vs and a low VT of −2.3 V are achieved which proved that 2,9-DPh-DNTT is an excellent organic semiconductor in the field such as a large-area display and sensor matrix, etc.