Effects of physical treatment of ITO electrodes on the electrical properties of pentacene thin-film transistors

We report that treating indium tin oxide (ITO) source and drain electrodes with ozone or oxygen (O2) plasma enhances the hole injection from these electrodes to pentacene semiconductor, thereby improving the performance of pentacene thin-film transistors. Synchrotron radiation photoelectron spectroscopy results showed that the ozone and O2 plasma treatments of the electrodes increased their work functions by about 0.4 and 1.0 eV, respectively, compared to the as-deposited ITO electrode. These increases in work function were found to lower the hole injection barrier, producing remarkable increases in the field-effect mobility.