Effects of postannealing process on the properties of RuO ₂ films and their performance as electrodes in organic thin film transistors or solar cells

RuO ₂ films were deposited on SiO ₂ (300 nm)/N++Si substrates using radio frequency magnetron sputtering at room temperature. As-deposited RuO ₂ films were annealed at different temperatures (100, 300, and 500 °C) and ambients (Ar, O ₂ and vacuum), and the resulting effects on the electrical and physical properties of RuO ₂ films were characterized. The effect of annealing atmosphere was negligible, however the temperature highly influenced the resistivity and crystallinity of RuO ₂ films. RuO ₂ films annealed at high temperature exhibited lower resistivity and higher crystallinity than as-deposited RuO ₂. To investigate the possibility to use RuO ₂ film as alternative electrodes in flexible devices, as-deposited and annealed RuO ₂ 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 cm ²/(V s) and on/off ratio ≈ 5 × 10 ⁵) with RuO ₂ S/D electrodes, the DSSC and OPV (3.5% and 2.56%) incorporating annealed RuO ₂ electrodes showed higher performance than those with as-deposited RuO ₂ electrodes (3.0% and 1.61%, respectively).