High optoelectronic quality of AZO films grown by RF-magnetron sputtering for organic electronics applications

Abstract

Aluminum-doped zinc oxide thin films, known by the acronym AZO, were grown by radio-frequency magnetron sputtering method (rf-magnetron sputtering) onto glass substrate at room temperature and without posterior heat treatment. The impact on the structural, electrical, and optical properties of the AZO films was studied as a function of the following deposition parameters: working pressure, rf-power and thickness. Our films showed low electrical resistivity and high transmittance in the visible region comparable to commercial indium tin oxide (ITO) films. We obtained an optimized AZO film with an electrical resistivity of 4.90 × 10−4 Ωcm and presented optical transmittance strikingly high for such a good conductor, with about 98% at 580 nm and an average optical transmittance of about 92% in the visible region. We also built and characterized an organic light-emitting diode (OLED) using the optimized AZO film as a transparent electrode. The AZO-based OLED showed characteristics comparable to a reference ITO-based device, indicating that AZO films have optoelectronic properties good enough to be used in organic electronics. In addition, the results suggest that they are suitable to be employed as transparent conductors in flexible polymeric substrates since their synthesis was performed without intentional heating.