Seeding-method-processed anatase TiO2 film at low temperature for efficient planar perovskite solar cell

Electron-selective layers (ESLs) processed at low temperature play a vital role for planar perovskite solar cells (PSCs), especially for flexible devices. In this scheme, a novel strategy namely seeding-method is developed to prepare highly-compact anatase TiO 2 ESLs at dramatically low temperature of 150 °C. This method allows the preparation of anatase TiO 2 via hydrolyzation of Titanium diisopropoxide bis (acetylacetonate) (TiAcAc) induced by TiO 2 crystal seed. Seeding-method permits the hydrolyzation of TiAcAc occurs at just 70 °C to obtain anatase TiO 2 , which is greatly reduced compared with normal procedure where 500 °C is desired . Accordingly, the acquired anatase TiO 2 reacted with hydrochloric acid to prepare Cl-doped TiO 2 (Cl@TiO 2 ). Highly-compact anatase TiO 2 ESLs were formed by spin-coating Cl@TiO 2 onto FTO and then annealed at 150 °C. Power conversion efficiency of planar PSCs based on anatase Cl@TiO 2 ESLs was 15.73%. Seeding-method processed at low temperature can be an effective way to advance the development of flexible perovskite photovoltaic.