title: Elucidating the charge carrier separation and working mechanism of CH3NH3PbI(3-x)Cl(x) perovskite solar cells.
abstract: Developments in organic-inorganic lead halide-based perovskite solar cells have been meteoric over the last 2 years, with small-area efficiencies surpassing 15%. We address the fundamental issue of how these cells work by applying a scanning electron microscopy-based technique to cell cross-sections. By mapping the variation in efficiency of charge separation and collection in the cross-sections, we show the presence of two prime high efficiency locations, one at/near the absorber/hole-blocking-layer, and the second at/near the absorber/electron-blocking-layer interfaces, with the former more pronounced. This 'twin-peaks' profile is characteristic of a p-i-n solar cell, with a layer of low-doped, high electronic quality semiconductor, between a p- and an n-layer. If the electron blocker is replaced by a gold contact, only a heterojunction at the absorber/hole-blocking interface remains.
authors.affiliation: Department of Materials and Interfaces, Faculty of Chemistry, Weizmann Institute of Science, Rehovot 76100, Israel.
authors.forename: Eran
authors.initials: E
authors.lastname: Edri
authors.affiliation: Department of Materials and Interfaces, Faculty of Chemistry, Weizmann Institute of Science, Rehovot 76100, Israel.
authors.forename: Saar
authors.initials: S
authors.lastname: Kirmayer
authors.affiliation: Department of Materials and Interfaces, Faculty of Chemistry, Weizmann Institute of Science, Rehovot 76100, Israel.
authors.forename: Sabyasachi
authors.initials: S
authors.lastname: Mukhopadhyay
authors.affiliation: Department of Chemical Research Support, Faculty of Chemistry, Weizmann Institute of Science, Rehovot 76100, Israel.
authors.forename: Konstantin
authors.initials: K
authors.lastname: Gartsman
authors.affiliation: Department of Materials and Interfaces, Faculty of Chemistry, Weizmann Institute of Science, Rehovot 76100, Israel.
authors.forename: Gary
authors.initials: G
authors.lastname: Hodes
authors.affiliation: Department of Materials and Interfaces, Faculty of Chemistry, Weizmann Institute of Science, Rehovot 76100, Israel.
authors.forename: David
authors.initials: D
authors.lastname: Cahen
mesh_terms: D017610:Calcium Compounds / Q000737:chemistry*; D002712:Chlorides / Q000737:chemistry; D056831:Coordination Complexes / Q000737:chemistry*; D011211:Electric Power Supplies; D007854:Lead / Q000737:chemistry; D018625:Microscopy, Atomic Force; D008855:Microscopy, Electron, Scanning; D010087:Oxides / Q000737:chemistry*; D012666:Semiconductors; D012993:Solar Energy; D014025:Titanium / Q000737:chemistry*
chemical_list: D017610:Calcium Compounds; D002712:Chlorides; D056831:Coordination Complexes; D010087:Oxides; C059910:perovskite; D007854:Lead; C029891:lead chloride; D014025:Titanium