Reduction of charge injection barrier by 1-nm contact oxide interlayer in organic field effect transistors

The enhancement of the charge injection process by the insertion of an ultrathin (∼1 nm) contact oxide interlayer (COI) at the metal/organic material interface in organic field effect transistors (OFETs) is reported. Six different oxides were used as COI, and Al₂O₃ was found to exhibit the highest OFET mobility with a reduction in the average contact resistance (R_c) from 19.9 to 1.9 kΩ·cm. Photoelectron yield spectroscopy analysis revealed that the insertion of COI increases the work function of an Au contact and reduces the charge injection barrier at the interface, which lowers R_c and, therefore, results in enhanced device performance.