Enhanced Photovoltaic Performance of Perovskite Solar Cells Using Polymer P(VDF-TrFE) as a Processed Additive

It is known that CH3NH3PbI3 perovskite films with high crystallization and controlled morphology always show enhanced power conversion efficiency. Here we incorporate a small amount of polyvinylidene fluoride–trifluoroethylene polymer P(VDF-TrFE) into PbI2 solution to control the crystallinity and morphology of perovskite layer in a two-step deposition process. Our results show that the P(VDF-TrFE) bridges the grain boundaries and also enhances the crystallinity of the perovskite layer significantly. By adjusting P(VDF-TrFE) concentration, the fabricated perovskite solar cells show improved average power conversion efficiency from 9.57 ± 0.25% to 12.54 ± 0.40% under a standard illumination of 100 milliwatts per square centimeter, which increases by nearly 31%. Thus, we demonstrate a new strategy to control the crystallinity and morphology of perovskite films by incorporating polymer into PbI2 film in a two-step deposition process. In addition, this method has been proven as an effective way to prepare high-performance perovskite solar cells.