Effects of postannealing process on the properties of RuO2 films and their performance as electrodes in organic thin film transistors or solar cells.

Dong-Jin Yun, Hye-min Ra, Sae Byeok Jo, Wanjoo Maeng, Seung-hyup Lee, Sunghoon Park, Ji-Wook Jang, Kilwon Cho, Shi-Woo Rhee

Index: ACS Appl. Mater. Interfaces 4(9) , 4588-94, (2012)

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Abstract

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).