Aluminum doped zinc oxide films grown by atomic layer deposition for organic photovoltaic devices

Aluminum doped zinc oxide (AZO) films were studied as an alternative transparent electrode material to indium tin oxide (ITO) in organic photovoltaic devices. The AZO films were prepared by atomic layer deposition from diethylzinc, water and trimethylaluminum precursors. The same number of deposition cycles resulted in 170 and 90 nm thick films at deposition temperatures of 150 and 250 °C, respectively. Uniform films with wedge-shaped crystallites were observed at both temperatures. The functionality of the AZO electrodes in photovoltaic applications was tested using known organic photoactive layers. Devices with AZO electrode showed comparable performance to the reference device where ITO was used as transparent electrode. Moreover, the devices with AZO electrode were stable in open air showing no degradation during 40 days time interval.