title: Electron-hole diffusion lengths exceeding 1 micrometer in an organometal trihalide perovskite absorber.
abstract: Organic-inorganic perovskites have shown promise as high-performance absorbers in solar cells, first as a coating on a mesoporous metal oxide scaffold and more recently as a solid layer in planar heterojunction architectures. Here, we report transient absorption and photoluminescence-quenching measurements to determine the electron-hole diffusion lengths, diffusion constants, and lifetimes in mixed halide (CH3NH3PbI(3-x)Cl(x)) and triiodide (CH3NH3PbI3) perovskite absorbers. We found that the diffusion lengths are greater than 1 micrometer in the mixed halide perovskite, which is an order of magnitude greater than the absorption depth. In contrast, the triiodide absorber has electron-hole diffusion lengths of ~100 nanometers. These results justify the high efficiency of planar heterojunction perovskite solar cells and identify a critical parameter to optimize for future perovskite absorber development.
authors.affiliation: University of Oxford, Clarendon Laboratory, Parks Road, Oxford OX1 3PU, UK.
authors.forename: Samuel D
authors.initials: SD
authors.lastname: Stranks
authors.forename: Giles E
authors.initials: GE
authors.lastname: Eperon
authors.forename: Giulia
authors.initials: G
authors.lastname: Grancini
authors.forename: Christopher
authors.initials: C
authors.lastname: Menelaou
authors.forename: Marcelo J P
authors.initials: MJ
authors.lastname: Alcocer
authors.forename: Tomas
authors.initials: T
authors.lastname: Leijtens
authors.forename: Laura M
authors.initials: LM
authors.lastname: Herz
authors.forename: Annamaria
authors.initials: A
authors.lastname: Petrozza
authors.forename: Henry J
authors.initials: HJ
authors.lastname: Snaith