CH₃NH₃PbI₃ layers have been prepared by two-step procedure (spin coating and dipping) on flat substrates under ambient conditions with uncontrolled relative humidity. The films have been characterized by means of scanning electron microscopy, absorption coefficient and x-ray diffraction when varying spinning rate, washing procedure, and dipping time. In particular a novel washing procedure has been developed to improve the film uniformity. The material has been tested as absorber layer in simplified solar cells by fabricating hole transport material free solar cells on flat substrates. The results demonstrate the possibility to realize planar solar cells even under uncontrolled conditions.