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Atomic Layer Deposition of PbS Thin Films at Low Temperatures

  • Georgi Popov*
  • , Goran Bačić
  • , Miika Mattinen
  • , Toni Manner
  • , Hannu Lindström
  • , Heli Seppänen
  • , Sami Suihkonen
  • , Marko Vehkamäki
  • , Marianna Kemell
  • , Pasi Jalkanen
  • , Kenichiro Mizohata
  • , Jyrki Räisänen
  • , Markku Leskelä
  • , Hanna Maarit Koivula
  • , Seán T. Barry
  • , Mikko Ritala*
  • *Corresponding author for this work
    • University of Helsinki
    • Carleton University
    • Aalto University

    Research output: Contribution to journal › Article › Scientific › peer-review

    Abstract

    Atomic layer deposition (ALD) is a viable method for depositing functional, passivating, and encapsulating layers on top of halide perovskites. Studies in that area have only focused on metal oxides, despite a great number of materials that can be made with ALD. This work demonstrates that, in addition to oxides, other ALD processes can be compatible with the perovskites. We describe two new ALD processes for lead sulfide. These processes operate at low deposition temperatures (45-155 °C) that have been inaccessible to previous ALD PbS processes. Our processes rely on volatile and reactive lead precursors Pb(dbda) (dbda = rac-N2,N3-di-tert-butylbutane-2,3-diamide) and Pb(btsa)2 (btsa = bis(trimethylsilyl)amide) as well as H2S. These precursors produce high quality PbS thin films that are uniform, crystalline, and pure. The films exhibit p-type conductivity and good mobilities of 10-70 cm² V-1 s-1. Low deposition temperatures enable direct ALD of PbS onto a halide perovskite CH3NH3PbI3 (MAPI) without its decomposition. The stability of MAPI in ambient air is greatly improved by capping with ALD PbS. More generally, these new processes offer valuable alternatives for PbS-based devices, and we hope that this study will inspire more studies on ALD of non-oxides on halide perovskites.

    Original languageEnglish
    Pages (from-to)8216−8228
    JournalChemistry of Materials
    Volume32
    Issue number19
    DOIs
    Publication statusPublished - 13 Oct 2020
    MoE publication typeA1 Journal article-refereed

    Funding

    We thank the Finnish Center of Excellence in Atomic Layer Deposition (ALDCoE 2012-2017) and additional support from the Academy of Finland (Decision Number 309552). G.P. acknowledges the doctoral program in Materials Research and Nanosciences (MATRENA) of the University of Helsinki as well as Emil Aaltonen foundation for funding and support. G.B. and S.T.B. acknowledge the QEII-OGSST program for funding and Carleton University for support. H.S. acknowledges the support from the Walter Ahlström Foundation.

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