Structural and Optical Properties of the Perovskite Layer on Well-Aligned ZnO Nanorods

To achieve highly efficient perovskite solar cells, it is important to design a metal oxide layer with high electron mobility. In this study, well-aligned ZnO nanorods (NRs) were prepared through the hydrothermal method using ZnO seed layers with varying thickness. The effect of the structural and optical properties of the perovskite layer deposited under the prepared conditions was systematically investigated via scanning electron microscopy, X-ray diffraction, ultraviolet-visible spectroscopy, and photoluminescence (PL) spectroscopy. The improved alignment of the ZnO NRs was found to affect the topography of the perovskite polycrystals, such as increased grain size and improved uniformity of the perovskite layer. The thicker the ZnO seed layer, the more enhanced the alignment of the ZnO NRs, resulting in larger and more uniform grains. The perovskite layer deposited on the well-aligned ZnO NRs exhibited increased absorbance and PL intensity without changing crystallinity. Our results will help improve the efficiency of high-quality perovskite devices based on ZnO electron transport layer.