engleski

Influence of the electron transport layer pre- treatment on the efficiency of perovskite solar cells

Inorganic materials commonly used as electron transfer layers (ETLs), such as TiO2, ZnO, and SnO2, are generally characterized by low cost, high stability and excellent electronic performance, and are more usually used in perovskite solar cells as mesoporous layers. Among these ETLs, TiO2 is the most studied material due to its high electron mobility, wide energy gap, and good chemical and physical stability. There are various methods to fabricate TiO2 ETL in both mesoporous and nanostructured thin-films, such as spin-coating, chemical bath deposition, magnetron sputtering, etc., but each of them require a multi-step process to prepare the layer. On the other hand, to produce a high-quality TiO2 dense and porous layer simply in only one step, an anodization method is proposed. By that method, a TiO2 compact layer and a TiO2 nanotube layer could be prepared by means of electrochemical oxidation of magnetron sputtered Ti-film on an indium tin oxide (ITO) substrate. In this work, we report the synthesis of TiO2 nanotubes as ETL for perovskite solar cells. The TiO2 nanotubes were prepared by anodizing a Ti/ITO substrate in a ethylene glycol electrolyte containing F– and H2O. The conventional spin- coating method and the anodization method for fabricating TiO2 nanotubes and the samples obtained by both methods were compared. The results indicate that a porous TiO2 layer and a compact one can be obtained simultaneously through the anodization process and serve as low-cost ETL for PSCs. In addition to that, when preparing the ETL by the anodization method, we pretreated the samples (Ti/ITO) in different atmospheres (O2, N2, air), and at different temperatures to get a better insight into the resulting morphology (length and shape) of the prepared nanotubes, and thus the improving properties of the titania layers as ETL in PSCs. The prepared films were thoroughly characterized by various methods such as Grazing Incidence X-Ray Diffraction (GIXRD), SEM, contact angle measurements, AFM and KPFM. Finally, the electrical properties were investigated using the Solid-State Impedance Spectroscopy (SS-IS) method.

electron transfer layer ; titania nanotubes ; GIXRD ; AFM ; SEM ; IS

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