Fabrication of perovskite solar cells by reaction between spin-coated precursor films and CH3NH3I vapor

The organic–inorganic hybrid perovskite CH3NH3PbI3 thin-films were obtained by reaction between spin-coated PbI2 precursor thin-films on a porous-TiO2 layer and CH3NH3I vapor. The dependence of the photovoltaic properties of solar cells fabricated with these films on the CH3NH3I powder source temperature and reaction time was investigated. The obtained thin-films were characterized using X-ray diffraction and scanning electron microscopy. The best power conversion efficiencies (PCEs) for each heating condition were 160 °C for 30 min, 150 °C for 45 min, and 140 °C for 60 min. The presence of PbI2 and CH3NH3PbI3 layers, and a flatter and more compact morphology, led to relatively high PCE. The perovskite thin-films were annealed in a N2 atmosphere and the effect of annealing temperature on the photovoltaic performance was also investigated. The PCE for a solar cell fabricated using CH3NH3PbI3 thin-films annealed in the range from 130 to 150 °C for 1 h was over 4%.