The role of sulfur in sulfur-doped copper(I) iodide p-type transparent conductors

Adeem Saeed Mirza (Corresponding author), Mike Pols, Wiria Soltanpoor, Shuxia Tao, Geert H.L.A. Brocks, Monica Morales-Masis (Corresponding author)

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CuI has been the best-known p-type transparent conductor (TC) for years, yet its conductivity still lags behind n-type TCs. Herein, we demonstrate S-doped CuI films via pulsed laser deposition and provide an in-depth defect analysis to describe its enhanced conductivity. Combining compositional and optoelectronic characterizations of the films, we show that 3 atom % S incorporation in CuI leads to an increase in hole carrier density from ∼8 × 1019 to ∼9 × 1020 cm−3, resulting in a conductivity boost from 78 to 435 S cm−1 while maintaining >75% transparency in the visible spectrum. The increase in carrier density is linked to the formation of a CuxS amorphous phase at grain boundaries and copper-vacancy-rich phases intragrain, the latter suggested by defect calculations. The high conductivities of the S:CuI films validate the recently reported high figure of merit and motivate further exploration of dopants and alloy strategies with CuI to achieve high-performing p-type TCs.
Original languageEnglish
Pages (from-to)4306-4320
Number of pages15
Issue number12
Publication statusPublished - 6 Dec 2023


The authors thank Dr. Yibin Bu for carrying out HAXPES, Mark Smithers for SEM-EDX, Henk Wolferen for making lamella via FIB for STEM measurements, and Dr. Martina Tsvetanova for STEM-EDX measurements, all at UT. The authors also thank Dr. Rachel Woods-Robinson and Dr. Yorick Birkhölzer for fruitful discussions during the project and Haibo Xue for discussions regarding DFT calculations. The authors acknowledge the financial support of the Dutch Research Council (NWO) StartUp 2019 project BRIDGE (project number STU.019.026). Conceptualization, A.S.M. and M.M.-M.; methodology, A.S.M. M.P. G.B. and M.M.-M.; investigation, A.S.M. and M.P.; formal analysis, A.S.M. M.P. W.S. S.T. G.B. and M.M.-M.; writing – original draft, A.S.M. and M.P.; writing – review & editing, A.S.M. M.P. W.S. S.T. G.B. and M.M.-M.; visualization, A.S.M. M.P. and M.M.-M.; supervision, M.M.-M.; funding acquisition, M.M.-M. The authors declare no competing interests. We support the inclusive, diverse, and equitable conduct of research.

FundersFunder number
Nederlandse Organisatie voor Wetenschappelijk OnderzoekSTU.019.026


    • MAP 3: Understanding
    • chalcogenide doping
    • copper iodide
    • optoelectronics
    • p-type transparent conductive materials
    • physical vapor deposition
    • pulsed laser deposition
    • semiconductors
    • transparency and conductivity
    • transparent electrodes
    • transparent electronics


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