ZrO₂/TiO₂ Electron Collection Layer for Efficient Meso-Superstructured Hybrid Perovskite Solar Cells

Since the first reports of efficient organic–inorganic perovskite solar cells in 2012, an explosion of research activity has emerged around the world, which has led to a rise in the power conversion efficiencies (PCEs) to over 20%. Despite the impressive efficiency, a key area of the device which remains suboptimal is the electron extraction layer and its interface with the photoactive perovskite. Here, we implement an electron collection “bilayer” composed of a thin layer of zirconia coated with titania, sitting upon the transparent conductive oxide fluorine-doped tin oxide (FTO). With this double collection layer we have reached up to 17.9% power conversion efficiency, delivering a stabilized power output (SPO) of 17.0%, measured under simulated AM 1.5 sunlight of 100 mW cm –2 irradiance. Finally, we propose a mechanism of the charge transfer processes within the fabricated architectures in order to explain the obtained performance of the devices.