Effects of Postannealing Process on the Properties of RuO2 Films and Their Performance As Electrodes in Organic Thin Film Transistors or Solar Cells

RuO2 films were deposited on SiO2 (300 nm)/N++Si substrates using radio frequency magnetron sputtering at room temperature. As-deposited RuO2 films were annealed at different temperatures (100, 300, and 500 °C) and ambients (Ar, O2 and vacuum), and the resulting effects on the electrical and physical properties of RuO2 films were characterized. The effect of annealing atmosphere was negligible, however the temperature highly influenced the resistivity and crystallinity of RuO2 films. RuO2 films annealed at high temperature exhibited lower resistivity and higher crystallinity than as-deposited RuO2. To investigate the possibility to use RuO2 film as alternative electrodes in flexible devices, as-deposited and annealed RuO2 films were applied as the source/drain (S/D) electrodes in organic thin film transistor (OTFT), catalytic electrodes in dye sensitized solar cell (DSSC) and as the hole-injection buffer layer (HIL) in organic photovoltaic (OPV). Except for OTFTs (μ ≈ 0.45 cm2/(V s) and on/off ratio ≈ 5× 105) with RuO2 S/D electrodes, the DSSC and OPV (3.5% and 2.56%) incorporating annealed RuO2 electrodes showed higher performance than those with as-deposited RuO2 electrodes (3.0% and 1.61%, respectively).