Properties of TiO2 Film Prepared by Anodization as Electron Transport Layer for Perovskite Solar Cells

The photovoltaic performance of perovskite solar cells (PSCs) largely depends on the characteristics of the electron transport layer (ETL). However, conventional solution-based processes may lead to obvious voids or cavities on the film. In this publication, an anodization process was proposed to transform a layer of Ti sputtered on a fluorine-doped indium tin oxide (FTO) substrate to TiO 2 nanotubes as an ETL for PSCs. Through a one-step anodization process in an electrolyte of ethylene glycol with NH 4 F and H 2 O, an integrated 500-nm-thick layer composed of a TiO 2 nanotube layer (mesoporous layer) and a TiO 2 compact layer was obtained. This method was simple and more efficient than the spin-coating process, and there were no traps between nanotube layer and compact layer. PSCs based on this ETL achieved the highest efficiency of 12.82%, which was comparable to devices whose ETLs were fabricated by a conventional spin-coating process.