Spray-coating as a facile and quantitative method was introduced to prepare thin and continuous TiO2 compact layers on different substrates for perovskite solar cells. The as-prepared film is. highly transparent and smooth, which is. of significance in perovskite solar cells to decrease incident light loss and facilitate the film cast and electric contact. The compact TiO2 layer shows excellent performance when coated with perovskite and assembled into a. device. Since it provides. unlimited substrate size, patterning function and the TiO2 used for spray-coating is well crystallized, this method has. huge potential for mass production and great adaptability for a variety of applications.