A Two-Step Absorber Deposition Approach To Overcome Shunt Losses in Thin-Film Solar Cells: Using Tin Sulfide as a Proof-of-Concept Material System

Vera Steinmann, Rupak Chakraborty, Paul Rekemeyer, Katy Hartman, Riley Brandt, Alex Polizzotti, Chuanxi Yang, Silvija Gradecak, Roy Gordon, Tonio Buonassisi

    Research output: Contribution to journalArticlepeer-review

    21 Scopus Citations

    Abstract

    As novel absorber materials are developed and screened for their photovoltaic (PV) properties, the challenge remains to reproducibly test promising candidates for high-performing PV devices. Many early-stage devices are prone to device shunting due to pinholes in the absorber layer, producing 'false-negative' results. Here, we demonstrate a device engineering solution toward a robust device architecture, using a two-step absorber deposition approach. We use tin sulfide (SnS) as a test absorber material. The SnS bulk is processed at high temperature (400 degrees C) to stimulate grain growth, followed by a much thinner, low-temperature (200 degrees C) absorber deposition. At a lower process temperature, the thin absorber overlayer contains significantly smaller, densely packed grains, which are likely to provide a continuous coating and fill pinholes in the underlying absorber bulk. We compare this two-step approach to the more standard approach of using a semi-insulating buffer layer directly on top of the annealed absorber bulk, and we demonstrate a more than 3.5x superior shunt resistance Rsh with smaller standard error ..sigma..Rsh. Electron-beam-induced current (EBIC) measurements indicate a lower density of pinholes in the SnS absorber bulk when using the two-step absorber deposition approach. We correlate those findings to improvements in the device performance and device performance reproducibility.
    Original languageAmerican English
    Pages (from-to)22664-22670
    Number of pages7
    JournalACS Applied Materials and Interfaces
    Volume8
    Issue number34
    DOIs
    StatePublished - 2016

    NREL Publication Number

    • NREL/JA-5J00-67109

    Keywords

    • device shunting
    • novel absorber materials
    • performance reliability
    • photovoltaics
    • thin-films
    • tin sulfide

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