Synthesis of thin film by self-assembly of perovskite nanosheets

Layered perovskite, K2NbO3F, includes rock-salt type KF blocks in a K2NiF4 type structure. After the KF blocks are dissolved selectively in water at room temperature, the resultant colloidal suspension consists of nanosheet forms. Positively charged K+ ions in colloidal suspension act as an inorganic binder in electrostatic self-assembly with an exfoliated perovskite nanosheet. In the present study, we synthesized a KNbO3 thin film on a quartz substrate using a self-assembly process. The thin film on a quartz substrate was characterized using XRD analysis. The molar extinction coefficient of the colloidal suspension and absorbance of the thin film were examined using UV-vis absorption spectra. Respective thicknesses of perovskite nanosheet aggregate thin films were examined using AFM. The UV-vis absorption spectra of the films showed an increase in absorbance with increasing immersion time, suggesting growth of a self-assembled multilayer comprising perovskite nanosheets and K+ ions.