Well-aligned ZnO nanorod arrays from diameter-controlled growth and their application in inverted polymer solar cell

Well-aligned ZnO nanorod arrays (ZNAs) with various growth time were fabricated on indium tin oxide (ITO) coated glass substrate using hydrothermal method. The average diameter of the ZnO nanorods ranged from 35 to 100 nm with elongating growth time from 0.5 to 3 h. The ZNAs had wurtzite-structured (hexagonal) ZnO and preferred growth along (0001) direction. When growth time was less than 2 h, the ZNAs showed very high optical transmission (> 80%) in visible light region. The formation of Ohmic contact between ZNAs and the substrates was also observed. Furthermore, solar cells consisted of ZNAs/polymer hybrid were fabricated, and a highest power conversion efficiency (PCE) of 1.11% from these devices was achieved. Moreover, The PCE of this device almost remained constant for long time when exposed to ambient atmosphere.