The efficiency and stability of perovskite solar cells (PSCs) depend on the performance of the charge-transporting layers (CTLs). Nowadays, most of the electron transport layers (ETLs) used in PSCs are based on transition metal oxides such as titanium oxide (TiO₂), tin(IV) oxide (SnO₂), and zinc oxide (ZnO). Active research is devoted to optimising the morphology of ETLs and their interfaces for subsequent perovskite deposition, improving the electronic properties of ETLs for efficient electron transport, and developing of e nanostructures to enable charge carrier extraction. Tin(IV) oxide occupies an important place in the transparent conductive oxide (TCO) family. Different routes and synthesis procedures for obtaining SnO₂ nanocrystals and nanostructures have been examined, including thermal evaporation, flame pyrolysis, hydrothermal synthesis, and various sol-gel methods, each of which has its own pros and cons.
In this work, we report on the synthesis and characterisation methods of SnO₂ nanoparticles and nanostructured thin films to control the size and morphology under different reaction conditions. We attempt to provide an insight into the processes of domain formation as a function of reaction conditions. The solvothermal technique for preparing SnO₂ nanorod arrays was systematically investigated. The impact of different growth parameters such as growth pressure, substrate orientation, seed layer type, and growth time on the morphology and other properties of the SnO₂ nanostructures was studied. The prepared samples were thoroughly (micro)structurally and electrically characterised using X-Ray Diffraction (XRD), atomic force microscopy (AFM), scanning electron microscopy (SEM), and impedance spectroscopy (IS). All this draws attention to the degree of chemical and structural homogeneity, and the influence of temperature and other reaction conditions on the growth and properties of SnO₂ nanostructures. We seek to more precisely control SnO₂ surface properties, including film quality, defects, and surface states, to facilitate charge transfer and diminish the recombination. The obtained results provide thorough information to the scientific community for synthesizing SnO₂ nanostructures with improved reproducibility for application in perovskite solar cells (PSCs).