Two local built-in potentials of H2S processed CZTSSe by complex impedance spectroscopy

Sanghyun Lee, Kent J. Price, Dae Hwan Kim

    Research output: Contribution to journalArticlepeer-review

    6 Scopus citations


    We have fabricated CZTSSe solar cells with H2S sulfo-selenization processes and investigated the electronic structure at the PN hetero- and back contact junctions by impedance spectroscopy. By decoupling each junction's impedance spectroscopic responses, we systematically characterized the built-in potential of two local junction interfaces. A developed equivalent circuit model has been optimized for decoupling each junction's property at different frequency bands. Modeling and numerical simulations were conducted with the in-house MATLAB modeling suites connected to external simulators of Sentaurus TCAD and LEVM/LEVMW software to estimate the impact of each junction component to impedance spectra. The optimized model is comprised of a parallel circuit combination with resistance and capacitor-like elements (constant phase elements), connected to one inductive element. The conversion efficiency of CZTSSe devices is 6.2% with bandgap energy 1.13 eV based on external quantum efficiency measurements. From the equivalent circuit model, the built-in potential of the hetero-junction is characterized as 956 meV, which is ~3% smaller than an ideal case from TCAD, 987 meV. Conversely, the built-in potential of the back contact junction is 476 meV. The apparent built-in potential is estimated as 480 meV from the Mott-Schottky equation.

    Original languageEnglish
    Pages (from-to)11-18
    Number of pages8
    JournalSolar Energy
    StatePublished - Sep 1 2021

    Bibliographical note

    Funding Information:
    This work was partially supported by the Louisville Gas & Energy and Kentucky Utility Foundation, Duke Energy Foundation, CSRC at Indiana State University, DGIST R&D Program of the Ministry of Science, and ICT(21-CoE-ET-01).

    Publisher Copyright:
    © 2021


    • Back contact junction
    • Built-in potential
    • CZTSSe
    • Hetero-junction
    • Interface
    • Spectroscopy

    ASJC Scopus subject areas

    • Renewable Energy, Sustainability and the Environment
    • Materials Science (all)


    Dive into the research topics of 'Two local built-in potentials of H2S processed CZTSSe by complex impedance spectroscopy'. Together they form a unique fingerprint.

    Cite this