Studies of organic complementary inverters with pentacene and PTCDI-C ₁₃H₂₇

We used the p-channel pentacene and n-channel PTCDI-C₁₃H ₂₇ thin film transistors (OTFTs) to compose an organic complementary inverter device. In the experiment this device was inserted a polyimide (PI) layer into the interface of a semiconductor and gate insulator to improve the orientation phase and decrease the leakage current for n- and p-type OTFTs simultaneously. The hysteresis behavior of the transistors and inverters exhibited high trapping and detrapping speeds for the traps between gate dielectric and semiconductor layers; therefore, the PI layer had functions for improving surface roughness and reducing the hysteresis behavior of gate-dielectrics. The hysteresis of pentacene and PTCDI-C₁₃H ₂₇ films with PI layer was smaller than that without PI obtained by capacitance-voltage measurements. Therefore, the p-type and n-type OTFTs with PI as modification layer had high field-effect mobility of 0.976 and 0.512 cm ²V^-1s^-1, on/off ratio of 1.7×10 ⁵ and 7×10⁴, threshold voltage of -10.76 and 12.21 V, respectively; by contrast, poor performance occurred in the device without PI layer. Additionally, a good performance for the organic inverter was achieved when pentacene and PTCDI-C₁₃H₂₇ films grown on the PI layer exhibited the match of surface energy between the semiconductor and PI and the large grain size. An organic complementary metal oxide semiconductor (O-CMOS) device had similar drain current, threshold voltage and mobility for n-type and p-type transistors by using the PI layer as surface modification of the dielectric layer. Compared with the device without the PI layer, there were higher noise margins and gains and lower power dissipation of the O-CMOS.