Ambipolar organic field-effect transistor and inverter: Hybrid fabrication and high photoresponse

Highly aligned, unidirectional crystalline array of an organic molecule, viz, N, N'-dioctyl-3,4,9,10-perylene tetracarboxylic diimide (PTCDI-C8) has been deposited in large area by solution self-assembly. A hybrid ambipolar organic field-effect transistor is designed comprising of crystalline assemblies of PTCDI-C8 and thin film of pentacene. The OFET exhibited high charge carrier mobilities, viz, μ~ 0.3 cm²/Vs and 0.4 cm²/Vs for electron and hole respectively. The static characteristics of the hybrid complementary inverter produced high gain ca. 20 and logic threshold of 30 V when biased at V_dd = 40 V. The transfer characteristics of the inverter could be controlled by exploiting the high photoresponse of PTCDI-C8, showing a shift of logic threshold from 30 V to 16.5 V under the incident illumination of different intensity.