Abstract
In this thesis, we have used silk fibroin as the gate dielectric layer and chosen PTCDI-C8 and F16CuPc as N-type semiconductor materials to fabricate organic thin-film transistors (OTFTs). PTCDI-C8 and F16CuPc were usually deposited on SiO2 in the fabrication of OTFTs. In the present work, PET was used as the substrate and silk fibroin as gate dielectric layer for flexible OTFTs. The device characteristics of N-type organic semiconductors were analyzed. The field-effect mobility (FE) value and on/off current ratio of PTCDI-C8 TFTs are 0.08 cm2V-1s-1 and 6.1x103, respectively. Although the FE value of PTCDI-C8 TFTs is less than the previously reported value of 1.3 cm2V-1s-1, the threshold voltage is 2.4 V much less than the reported value of ~ 10 V of OTFTs on SiO2/Si. F16CuPc is a n-type semiconductor material with air stability. We deposited F16CuPc onto silk fibroin at room temperature. The FE value of F16CuPc TFTs is 0.33 cm2V-1s-1 and the threshold voltage is 1.5 V. In contrast, the FE value of F16CuPc TFTs is only 0.005 cm2V-1s-1 if F16CuPc is deposited on SiO2 at room temperature. Furthermore, the FE value is 0.03 cm2V-1s-1 when F16CuPc is deposited on SiO2 at 125oC. It is very effective to enhance the mobility of F16CuPc TFTs by using silk fibroin as gate dielectric layer.