TiO(2)Colloid-Spray Coated Electron-Transporting Layers for Efficient Perovskite Solar Cells

Abstract

TiO(2)is one of the most efficient and widely used materials for electron-transporting layer (ETLs) in perovskite solar cells (PSCs). The formation of efficient TiO(2)layers is generally carried out at high temperature by baking at a temperature >400 degrees C or by vacuum deposition (e.g., atomic layer deposition and E-beam). In this study, the preparation of a TiO2ETL for PSCs is reported with excellent properties at low temperatures based on the synthesis of a stable TiO(2)colloidal aqueous solution and spray coating. The prepared TiO(2)colloids are able to produce a dense and uniform ETL even if it is simply dried at 100 degrees C after spray coating. It is believed that this is owing to the peroxo functional group remaining on the surface of the TiO(2)colloids. The TiO(2)ETLs, combined with the TiO(2)underlayer formed by chemical bath deposition, and the sprayed TiO(2)colloids allowed the fabrication of PSCs with performance similar to those of PSCs produced by annealing at 450 degrees C with a TiO(2)paste. The PSCs fabricated entirely at 100 degrees C demonstrated power conversion efficiency of 22.7% in small cells, and 19.0% in mini-modules.