All-Nanoparticle SnO 2 /TiO 2 Electron-Transporting Layers Processed at Low Temperature for Efficient Thin-Film Perovskite Solar Cells

Abstract

Solution-processed metal halide perovskite materials haverevealed outstanding optoelectronic features that make them uniquely suitedfor photovoltaic applications. Although a rapidprogresshasledtoperformances similar to inorganic thinfilm technologies, the fabricationmethod of some of the most widely used electron selective layers, based oneither mesoporous architectures or high annealing temperatures, may limit yeta future large-scale production. In that regard, planar perovskite solar cellconfigurations that can be processed at low temperatures are more desirable.Herein, we demonstrate that a few tens of nanometers thick bilayer, made oftwo types of inorganic oxide nanoparticles, can perform as a robust and low-temperature-processed electron-selective contact for planar perovskite solarcells. Aside from boosting the average efficiency of planar opaque devices, theproposed method allowed us to preserve the main photovoltaic characteristicswhen thinner active layers, usually exhibiting a noncontinuous morphology, were integrated for semitransparent cells. Byproviding excellent electronic and coverage features against the bottom electrode, this novel configuration may hence offer analternative route to approach future inexpensive printable methodologies for the fabrication of efficient low-temperatureperovskite solar cells.