Solution processed copper tetrabenzotriazaporphyrin films for organic field effect transistors

Abstract

Experimental characteristics of bottom-gate-contact organic thin film field-effect transistors (OTFTs) with 70 nm thick films of solution processed non-peripherally octahexyl-substituted copper tetrabenzotriazaporphyrin (6CuTBTAP) novel asymmetric molecules as active layers on silicon substrates are analyzed by both linear and non-linear parameter extraction methods in order to examine the field-dependent mobility and contact effects. Both linear and saturation field effect mobilities of OTFTs have been computationally determined as a function of gate voltage in the presence of the contact resistances. The Poole-Frankel mechanism is found to be responsible for charge transport during the saturation regime, giving the highest mobility of 6.9 × 10^−2 cm2 V^−1 s^−1 at the gate-source voltage (VG) of 50 V. The on-off ratio is found to be 106. The contact resistance at the interface between gold electrodes and the 6CuTBTAP active layer decreases with VG sharply from 75 MΩ corresponding to VG = 0 V to 10 MΩ once the transistor is turned on at the threshold voltage.