Dielectric surface-polarity tuning and enhanced operation stability of solution-processed organic field-effect transistors

Abstract

The electrical performance of triethylsilylethynyl anthradithiophene (TES-ADT) organic field-effect transistors (OFETs) was significantly affected by dielectric surface polarity controlled by grafting hexamethyldisilazane and dimethyl chlorosilane-terminated polystyrene (PS-Si(CH3)(2)Cl) to 300-nm-thick SiO2 dielectrics. On the untreated and treated SiO2 dielectrics, solvent-vapor annealed TES-ADT films contained millimeter-sized crystals with low grain boundaries (GBs). The operation and bias stability of OFETs containing similar crystalline structures of TES-ADT could be significantly increased with a decrease in dielectric surface polarity. Among dielectrics with similar capacitances (10.5-11 nF cm(-2)) and surface roughnesses (0.40-0.44 nm), the TES-ADT/PS-grafted dielectric interface contained the fewest trap sites and therefore the OFET produced using it had low-voltage operation and a charge-carrier mobility similar to 1.32 cm(2) V (-1) s (-1), on-off current ratio > 10(6), threshold voltage similar to 0 V, and long-term operation stability under negative bias stress. (C) 2014 Elsevier B.V. All rights reserved.