MOF-derived ZnO as electron transport layer for improving light harvesting and electron extraction efficiency in perovskite solar cells

We adopt Metal-Organic-Framework (MOF)-derived zinc oxide (ZnO) as electron extraction material for hybrid cationic perovskite solar cells for the first time, breaking the prevailing paradigm of using oxides nanoparticle as electron extraction layer. MOF-derived ZnO with a polyhedral morphology and abundant internal porous structure can increase light harvesting ability and optimize the interfacial contact with perovskite. In contrast to conventional ZnO nanoparticles, the introduction of MOF-derived ZnO will achieve more efficient electron extraction, reduction of trapped state density and lower electron-hole recombination probability, thus significantly increase the fill factor and short-circuit current density of the cells. MOF-derived ZnO based perovskite solar cells exhibit a champion power conversion efficiency of 18.1% coupled with improved fill factor of 0.74 and short-circuit current density of 22.1 mA cm−2. Simultaneously, there is almost no hysteresis effect, and performance attenuation of the device in the ambient atmosphere over time can be suppressed. The performance improvement of perovskite solar cells stems from improved light harvesting efficiency in a wide wavelength range, as well as enhanced carrier extraction efficiency resulted from the increase of interface area between MOF-derived ZnO and perovskites.