Anatase TiO2 sol as a low reactive precursor to form the photoanodes with compact films of dye-sensitized solar cells

► The nanoparticles in anatase TiO2 sol were ultrafine, uniform sized and highly dispersed. ► The compact layer was prepared by LBL self assembly method, which was dense and comparable to that from physical route. ► The 12-layer LBL film of the DSSC led to a 24.5% increment in the conversion efficiency. ► Both porous layer and the compact layer of the DSSCs were derived from the anatase sol.