High-performance organic field-effect transistors based on copper/copper sulphide bilayer source-drain electrodes

We demonstrate an organic field-effect transistor (OFET) using copper (Cu) and copper sulfide (CuxS) as the source-drain electrodes. The OFET using Cu/CuxS results in a fivefold higher field-effect mobility and a 12 V reduction in threshold voltage as compared with the conventional devices with gold electrodes. The improvements of device performances are attributed to the enhancement of charge-injection. X-ray photoelectron spectroscopy revealed that sulfate ions were formed during deposition, which is considered to be responsible for the improvements.