Organometallic halide perovskite materials have a variety of remarkable optoelectronic properties, such as suitable band gap (1.5eV), high absorption coefficient, long carrier diffusion lengths and lifetimes. All these unique characters pave the way for perovskite-based devices, especially the photovoltaic cells. This presentation will start with the variation of the surface potential, photo-generated voltage, and photocurrent networks of perovskite solar cells (PSCs) with different film topography has been studied by coupling scanning Kelvin probe force microscopy (SKPM) and photoconductive atomic force microscopy (pcAFM). Then a series of TiO₂ compact films was prepared by sol-gel method with different sol aging time resulting in change of, thickness, surface roughness and compactness. High roughness of the films benefits the light absorption of perovskite layer and the injection efficiency at interface. The films with better compactness perform better hole blocking effect. The Ag@TiO₂ nanoparticles made by polyol solution method are embedded in perovskite films, resulting in an enhanced short-circuit current density due better light absorption and reduced charge recombination. Finally, both excess CH₃NH₃Cl and thiourea were introduced into the pristine CH₃NH₃PbI₃ precursor for antisolvent precipitation at low temperature and fabricated high quality perovskite films with desired morphology, crystallinity and optical properties. CH₃NH₃Cl exerted significant impacts on the perovskite crystallization process by controlling the delivery speed of PbI₂ from the intermediate phase CH₃NH₃I₂Cl. Further tuning the chemical composition with controlled film growth condition resulted in an average power conversion efficiency above 21% under the standard light illumination condition.