XPS depth profiles of organo lead halide layers and full perovskite solar cells by variable-size argon clusters

Yan Busby, Celine Noël, Sara Pescetelli, Antonio Agresti, Aldo Di Carlo, Jean Jacques Pireaux, Laurent Houssiau

    Research output: Contribution in Book/Catalog/Report/Conference proceedingConference contribution

    Abstract

    Organic and inorganic materials are more and more frequently combined in high-performance hybrid electronic and photonic devices. For such multilayered stacks, the identification of layers and interface defects by depth profile analysis is a challenging task, especially because of the possible ion beam induced modifications. This is particularly true for perovskite solar cells stacks that in a mesoscopic structure usually combine a metal electrode, a mesoscopic conductive oxide layer, an intrinsically hybrid light absorber, an organic hole extraction layer and a metal counter electrode. While depth profile analysis with X-ray photoelectron spectroscopy (XPS) was already applied to investigate these devices, the X-ray and ion beam induced modifications on such hybrid layers have not been previously investigated. In this work we compare the profiles obtained with monatomic Ar+ beam at different energies, with the ones obtained with argon ion clusters (Arn +) with different sizes (150<n<1000) and energies (up to 8 keV). A systematic study is performed on full mesoscopic perovskite (CH3NH3PbI3) solar cells and on model hybrid samples ((FAxCs1-xPbI3)0.85 (MAPbBr3)0.15)/TiO2). The results show that for monatomic beams, the implantation of positively charged atoms induces the surface diffusion of free iodine species from the perovskite which modifies the I/Pb ratio. Moreover, lead atoms in the metallic state (Pb0) are found to accumulate at the bottom of the perovskite layer where the Pb0 /Pbtot fraction reaches 50%. With argon clusters, the ion beam induced diffusion of iodine is reduced only when the etch rate is sufficiently high to ensure a profile duration comparable with low-energy Ar+. Convenient erosion rates are obtained only for n=300 and n=500 clusters at 8 keV, which have also the advantage of preserving the TiO2 surface chemistry. However, with argon cluster ions, Pb0 particles in the perovskite are less efficiently sputtered which leads to the increase of the Pb0 /Pbtot fraction (up to 75%) at the perovskite/TiO2 interface. Finally, ion beam and X-ray induced artifacts on perovskite absorbers can be reasonably neglected for fast analysis conditions in which the exposure time is limited to few hours.

    Original languageEnglish
    Title of host publicationPhysical Chemistry of Semiconductor Materials and Interfaces XVII
    EditorsHugo A. Bronstein, Felix Deschler, Thomas Kirchartz
    PublisherSPIE
    Volume10724
    ISBN (Electronic)9781510620193
    DOIs
    Publication statusPublished - 1 Jan 2018
    EventPhysical Chemistry of Semiconductor Materials and Interfaces XVII 2018 - San Diego, United States
    Duration: 20 Aug 201823 Aug 2018

    Conference

    ConferencePhysical Chemistry of Semiconductor Materials and Interfaces XVII 2018
    CountryUnited States
    CitySan Diego
    Period20/08/1823/08/18

    Keywords

    • Argon Clusters
    • Depth profiling
    • Hybrid Devices
    • Perovskite
    • Solar Cells
    • XPS

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