Anode material based on Zr-doped ZnO thin films for organic light-emitting diodes

Abstract

Zr-doped ZnO (ZZO) thin films have been investigated as an anodematerial, a potential alternative to indium tin oxide (ITO), for organic light emitting diode(OLED)devices. ZZO films have been deposited on glass substrates by pulsed laser deposition. The electrical and optical properties of these films were studied as a function of substrate temperature and oxygen pressure during deposition. For a 200-nm-thick ZZO filmgrown at 250 °C in 1 mTorr of oxygen, a resistivity of 5.6×10 −4 Ω cm was measured and an average optical transmittance of 84% was measured in the visible range (400–700 nm). The ZZO films,grown at different oxygen pressures, were used as an anode contact for OLEDdevices. External electroluminescence quantum efficiencies (0.8%–0.9%) comparable to those (0.9%–1.0%) measured for control devices fabricated on commercial ITO anodes were obtained at high current densities (1000 A/m 2 ). These results demonstrate that ZZO is a good anodematerial. In addition, it is an attractive alternative to ITO due to its low price and lack of toxicity.