title: Gold and iodine diffusion in large area perovskite solar cells under illumination.
abstract: Operational stability is the main issue hindering the commercialisation of perovskite solar cells. Here, a long term light soaking test was performed on large area hybrid halide perovskite solar cells to investigate the morphological and chemical changes associated with the degradation of photovoltaic performance occurring within the devices. Using Scanning Transmission Electron Microscopy (STEM) in conjunction with EDX analysis on device cross sections, we observe the formation of gold clusters in the perovskite active layer as well as in the TiO2mesoporous layer, and a severe degradation of the perovskite due to iodine migration into the hole transporter. All these phenomena are associated with a drastic drop of all the photovoltaic parameters. The use of advanced electron microscopy techniques and data processing provides new insights on the degradation pathways, directly correlating the nanoscale structure and chemistry to the macroscopic properties of hybrid perovskite devices.
authors.affiliation: Department of Materials Science & Metallurgy, University of Cambridge, 27 Charles Babbage road, CB3 0FS, Cambridge, UK. sc862@cam.ac.uk.
authors.forename: S
authors.identifier: http://orcid.org/0000-0001-9667-8972
authors.initials: S
authors.lastname: Cacovich
authors.affiliation: C.H.O.S.E. (Centre for Hybrid and Organic Solar Energy), Department of Electronic Engineering, University of Rome "Tor Vergata", via del Politecnico 1, Rome 00133, Italy and Cicci Research srl, via Giordania 227, 58100 Grosseto, Italy.
authors.forename: L
authors.identifier: http://orcid.org/0000-0003-3508-2475
authors.initials: L
authors.lastname: Ciná
authors.affiliation: C.H.O.S.E. (Centre for Hybrid and Organic Solar Energy), Department of Electronic Engineering, University of Rome "Tor Vergata", via del Politecnico 1, Rome 00133, Italy.
authors.forename: F
authors.initials: F
authors.lastname: Matteocci
authors.affiliation: Department of Materials Science & Metallurgy, University of Cambridge, 27 Charles Babbage road, CB3 0FS, Cambridge, UK. sc862@cam.ac.uk.
authors.forename: G
authors.initials: G
authors.lastname: Divitini
authors.affiliation: Department of Materials Science & Metallurgy, University of Cambridge, 27 Charles Babbage road, CB3 0FS, Cambridge, UK. sc862@cam.ac.uk.
authors.forename: P A
authors.initials: PA
authors.lastname: Midgley
authors.affiliation: C.H.O.S.E. (Centre for Hybrid and Organic Solar Energy), Department of Electronic Engineering, University of Rome "Tor Vergata", via del Politecnico 1, Rome 00133, Italy.
authors.forename: A
authors.initials: A
authors.lastname: Di Carlo
authors.affiliation: Department of Materials Science & Metallurgy, University of Cambridge, 27 Charles Babbage road, CB3 0FS, Cambridge, UK. sc862@cam.ac.uk.
authors.forename: C
authors.initials: C
authors.lastname: Ducati