Influence of air annealing on high efficiency planar structure perovskite solar cells

In the past few years, lead halide perovskite solar cell power conversion efficiencies have risen by using a wide variety of fabrication methods and just passed 20%. Perovskite solar cells are typically fabricated in a glovebox to strictly avoid any water exposure. A dry atmosphere significantly increases equipment and operational costs for industrial processes, so ambient perovskite fabrication will be less expensive and more attractive. In this work it is demonstrated that ambient annealing is comparable to annealing in dry N₂. Perovskite films annealed in a standard dry N₂ environment are compared with those annealed in ambient environment with 50% relative humidity. Solar cell devices were prepared with a planar structure configuration and annealed at one of three different temperatures (105, 115, or 125 °C) in either N₂ or ambient air. For all temperatures, the average efficiencies for the devices annealed in air are higher than those annealed in dry N₂. The highest efficiency achieved for air-annealed devices is 12.7%. Thus, good efficiency cells can be fabricated in an ambient environment, which facilitates mass production.