Growth of vertically aligned ZnO nanowalls for inverted polymer solar cells

This paper reports a facile fabrication of vertical ZnO nanowalls on ITO coated glass substrates by using an aqueous solution growth method at low temperature. The formation of nanowalls is ascribed to selective dissolution of (001) planes of the chemical bath deposited dense ZnO rods. The morphology of the etched ZnO nanowalls is determined by the structure of the as-grown ZnO rod arrays, which can be readily controlled by tuning aqueous solution parameters such as: initial pH value of chemical bath solution and the growth temperature. With verticaly aligned ZnO nanowalls as electrode in inverted polymer solar cells, the average performance of devices with open circuit voltage, short circuit current density, fill factor, and power conversion efficiency are measured as 0.56 V, 7.56 mW cm−2, 0.49 and 2.14%, respectively. The results indicate that the two-dimensional structure of ZnO nanowalls can effectively serve as an electrode for inverted polymer solar cells.