Interface engineering of highly efficient perovskite solar cells

A layered approach improves solar cells Perovskite films received a boost in photovoltaic efficiency through controlled formation of charge-generating films and improved current transfer to the electrodes. Zhou et al. lowered the defect density of the film by controlling humidity while the perovskite film formed from lead chloride and methylammonium iodide. Low-temperature processing steps allowed the use of materials that draw current out of the perovskite layer more efficiently. These and other modifications enabled a maximum cell efficiency of just over 19% and an average of 16.6%. Science, this issue p. 542 Optimizing the growth conditions of the perovskite layer and interlayer carrier transport boosts solar cell efficiency. Advancing perovskite solar cell technologies toward their theoretical power conversion efficiency (PCE) requires delicate control over the carrier dynamics throughout the entire device. By controlling the formation of the perovskite layer and careful choices of other materials, we suppressed carrier recombination in the absorber, facilitated carrier injection into the carrier transport layers, and maintained good carrier extraction at the electrodes. When measured via reverse bias scan, cell PCE is typically boosted to 16.6% on average, with the highest efficiency of ~19.3% in a planar geometry without antireflective coating. The fabrication of our perovskite solar cells was conducted in air and from solution at low temperatures, which should simplify manufacturing of large-area perovskite devices that are inexpensive and perform at high levels.