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.
Optical properties of methylammonium lead bromide (MAPbBr 3) perovskite single crystals grown using a seed-induced inverse temperature crystallization method were studied using photoluminescence (PL) and time-resolved PL measurements. Crystallization rate was observed to be faster with an increasing crystallization temperature. The highest crystal quality was recorded for a sample crystallized at 85 °C, and it exhibited the strongest X-ray diffraction peaks and PL intensity. The PL spectra for all samples crystallized at room temperature showed an asymmetric shape with a shoulder in the low energy side; this can be attributed to a photon recycling effect caused by re-emission inside the single crystal. We confirmed that the structural and optical properties of MAPbBr 3 single crystals can be manipulated by modifying the crystallization temperature.
Antisolvent treatment methods used to manufacture high-quality perovskite films using solution processes vary in terms of the type of antisolvent and processing condition employed. We analyzed the structural dependences of a perovskite film in terms of the applied volume of ethyl acetate as an antisolvent and the optical properties resulting therefrom. The application of an excessive volume of the antisolvent caused excessive pinholes in the entire area of the perovskite film. In addition, the pinholes were found to hinder the transport of charge carriers.
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