Article

Facet-dependent photovoltaic efficiency variations in single grains of hybrid halide perovskite

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Abstract

Photovoltaic devices based on hybrid perovskite materials have exceeded 22% efficiency due to high charge-carrier mobilities and lifetimes. Properties such as photocurrent generation and open-circuit voltage are influenced by the microscopic structure and orientation of the perovskite crystals, but are difficult to quantify on the intra-grain length scale and are often treated as homogeneous within the active layer. Here, we map the local short-circuit photocurrent, open-circuit photovoltage, and dark drift current in state-of-the-art methylammonium lead iodide solar cells using photoconductive atomic force microscopy. We find, within individual grains, spatially correlated heterogeneity in short-circuit current and open-circuit voltage up to 0.6 V. These variations are related to different crystal facets and have a direct impact on the macroscopic power conversion efficiency. We attribute this heterogeneity to a facet-dependent density of trap states. These results imply that controlling crystal grain and facet orientation will enable a systematic optimization of polycrystalline and single-crystal devices for photovoltaic and lighting applications.

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Author information

Affiliations

  1. The Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA

    • Sibel Y. Leblebici
    • , Linn Leppert
    • , Sebastian E. Reyes-Lillo
    • , Sebastian Wickenburg
    • , Ed Wong
    • , Jiye Lee
    • , Mauro Melli
    • , Dominik Ziegler
    • , Daniel K. Angell
    • , D. Frank Ogletree
    • , Paul D. Ashby
    • , Jeffrey B. Neaton
    •  & Alexander Weber-Bargioni
  2. Department of Materials Science and Engineering, University of California, Berkeley, California 94720, USA

    • Sibel Y. Leblebici
  3. Department of Physics, University of California, Berkeley, California 94720, USA

    • Linn Leppert
    • , Sebastian E. Reyes-Lillo
    •  & Jeffrey B. Neaton
  4. Joint Center for Artificial Photosynthesis and Chemical Science Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California 94720, USA

    • Yanbo Li
    • , Francesca M. Toma
    •  & Ian D. Sharp
  5. Scuba Probe Technologies LLC, 255 Lina Ave, Alameda, California 94501, USA

    • Dominik Ziegler
  6. Kavli Energy NanoSciences Institute at Berkeley, Berkeley, California 94720, USA

    • Jeffrey B. Neaton

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Contributions

S.Y.L., L.L., F.M.T., I.D.S. and A.W.-B. conceived the work and designed the research strategy. S.Y.L. measured and analysed the cAFM data. E.W., M.M. and D.K.A. participated in and supported the development of the new cAFM technique. J.L., D.Z., P.D.A., D.F.O., S.W., F.M.T., I.D.S. and A.W.-B. participated in interpretation of the experimental data. L.L. and S.E.R.-L. performed the theoretical calculations supervised by J.B.N. Y.L. performed the sample preparation and macroscale characterization. I.D.S. and F.M.T. supervised the sample preparation and characterization. S.Y.L., L.L., D.F.O., I.D.S. and A.W.-B. wrote the manuscript with help from D.Z., P.D.A., and F.M.T. F.M.T., J.B.N., I.D.S. and A.W.-B. coordinated this research. All authors contributed to the scientific discussion and manuscript revisions.

Competing interests

The authors declare no competing financial interests.

Corresponding authors

Correspondence to Ian D. Sharp or Alexander Weber-Bargioni.

Supplementary information

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    Supplementary Information

    Supplementary Methods, Supplementary Notes 1–3, Supplementary Discussion, Supplementary Figures 1–20, Supplementary Tables 1 and 2, Supplementary References.