The electronic structure of metal oxide/organo metal halide perovskite junctions in perovskite based solar cells

Cross-sections of a hole-conductor-free CH(3)NH(3)PbI(3) perovskite solar cell were characterized with Kelvin probe force microscopy. A depletion region width of about 45 nm was determined from the measured potential profiles at the interface between CH(3)NH(3)PbI(3) and nanocrystalline TiO(2), whereas a negligible depletion was measured at the CH(3)NH(3)PbI(3)/Al(2)O(3) interface. A complete solar cell can be realized with the CH(3)NH(3)PbI(3) that functions both as light harvester and hole conductor in combination with a metal oxide. The band diagrams were estimated from the measured potential profile at the interfaces, and are critical findings for a better understanding and further improvement of perovskite based solar cells.