Abstract
This work is to synthesize new naphthalene diimide derivatives with different substituted side groups as organic semiconductor materials for future flexible electronic applications. Naphthalene diimide derivatives were spin-coated onto substrate via spin-coating process in air as semiconductor materials for OTFT fabrication using SiO2 or poly(vinyl- phenol) PVP as dielectrics. Electrical characteristics measurement and air-stability tests of OTFTs were carried out in air. For low-cost and low temperature process of organic thin film transistor (OTFT) applications, this work is mainly focused on developing new soluble, high air-stability semiconducting materials. The studies include improving solubility of organic semiconductor materials, fabricating OTFT devices via spin-coating process in air, and increasing organic semiconductor air-stability. Results show that three n-type organic material, 1,4,5,8- naphthalene-tetracarboxylic diimide derivatives material with alkyl, phenyl, and (trifluoro-methyl)-benzyl groups (NTCDI-C, NTCDI-P, and NTCDI-F) were successfully synthesized and deposited on a SiO2/Si or PVP/SiO2 wafer by the spin-coating process in air. The grain sizes of above NTCDI-derivatives thin films were 2-3 □m, 500-650 nm, and 300-400 nm, respectively. Transistor characteristics of OTFTs using NTCDI-derivatives as semiconductor layers were measured in air, with the motilities of about 10-3 cm2V-1s-1 for NTCDI-F and NTCDI-P. The NTCDI-F OTFTs also exhibit air-stability with only slight mobility degradation after exposure in air for 7 days. In a summary, a new solution-processed n-type semiconductor material, NTCDI-F, has been synthesized and investigated for OTFT fabrication via spin-coating process in air. Transistor characteristics and air-stability of OTFTs using NTCDI-F as semiconductor layers have been achieved. Results have demonstrated the feasibility of using solution-processed NTCDI-derivatives as semiconductors via spin- coating process in air for OTFT fabrication for future applications in flexible integrated circuits (ICs).