Design of low bandgap tin–lead halide perovskite solar cells to achieve thermal, atmospheric and operational stability


Low bandgap tin–lead iodide perovskites are key components of all-perovskite tandem solar cells, but can be unstable because tin is prone to oxidation. Here, to avoid a reaction with the most popular hole contact, we eliminated polyethylenedioxythiophene:polystyrenesulfonate as a hole transport layer and instead used an upward band offset at an indium tin oxide–perovskite heterojunction to extract holes. To suppress oxidative degradation, we improved the morphology to create a compact and large-grained film. The tin content was kept at or below 50% and the device capped with a sputtered indium zinc oxide electrode. These advances resulted in a substantially improved thermal and environmental stability in a low bandgap perovskite solar cell without compromising the efficiency. The solar cells retained 95% of their initial efficiency after 1,000 h at 85 °C in air in the dark with no encapsulation and in a damp heat test (85 °C with 85% relative humidity) with encapsulation. The full initial efficiency was maintained under operation near the maximum power point and near 1 sun illumination for over 1,000 h.

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Fig. 1: Replacement of PEDOT:PSS with an ITO–perovskite heterojunction as the hole contact.
Fig. 2: Thermal and atmospheric stability of tin-lead perovskite solar cells.
Fig. 3: Morphology dependence of tin–lead perovskite oxidation.
Fig. 4: Normalized performance as a function of ageing time for FA0.75Cs0.25Sn0.4Pb0.6I3 solar cells.

Data availability

The data that support the plots within this article and other findings of this study are available from the corresponding author upon reasonable request.


  1. 1.

    Leijtens, T., Bush, K. A., Prasanna, R. & McGehee, M. D. Opportunities and challenges for tandem solar cells using metal halide perovskite semiconductors. Nat. Energy 3, 828–838 (2018).

    Google Scholar 

  2. 2.

    Hörantner, M. T. et al. The potential of multijunction perovskite solar cells. ACS Energy Lett. 2, 2506–2513 (2017).

    Google Scholar 

  3. 3.

    Eperon, G. E. et al. Perovskite–perovskite tandem photovoltaics with optimized band gaps. Science 354, 861–865 (2016).

    Google Scholar 

  4. 4.

    Palmstrom, A. F. et al. Enabling flexible all-perovskite tandem solar cells. Joule 3, 2193–2204 (2019).

    Google Scholar 

  5. 5.

    Rajagopal, A., Liang, P.-W., Chueh, C.-C., Yang, Z. & Jen, A. K.-Y. Passivation via graded fullerene heterojunction in low bandgap Pb–Sn binary perovskite photovoltaics. ACS Energy Lett. 2, 2531–2539 (2017).

    Google Scholar 

  6. 6.

    Leijtens, T. et al. Tin–lead halide perovskites with improved thermal and air stability for efficient all-perovskite tandem solar cells. Sustain. Energy Fuels 2, 2450–2459 (2018).

    Google Scholar 

  7. 7.

    Forgács, D. et al. Efficient monolithic perovskite/perovskite tandem solar cells. Adv. Energy Mater. 8, 1602121 (2016).

    Google Scholar 

  8. 8.

    Zhao, D. et al. Efficient two-terminal all-perovskite tandem solar cells enabled by high-quality low-bandgap absorber layers. Nat. Energy 3, 1093–1100 (2018).

    Google Scholar 

  9. 9.

    Eperon, G. E., Hörantner, M. T. & Snaith, H. J. Metal halide perovskite tandem and multiple-junction photovoltaics. Nat. Rev. Chem. 1, 0095 (2017).

    Google Scholar 

  10. 10.

    Hao, F., Stoumpos, C. C., Chang, R. P. H. & Kanatzidis, M. G. Anomalous band gap behavior in mixed Sn and Pb perovskites enables broadening of absorption spectrum in solar cells. J. Am. Chem. Soc. 136, 8094–8099 (2014).

    Google Scholar 

  11. 11.

    Prasanna, R. et al. Band gap tuning via lattice contraction and octahedral tilting in perovskite materials for photovoltaics. J. Am. Chem. Soc. 139, 11117–11124 (2017).

    Google Scholar 

  12. 12.

    Noel, N. K. et al. Lead-free organic–inorganic tin halide perovskites for photovoltaic applications. Energy Environ. Sci. 7, 3061–3068 (2014).

    Google Scholar 

  13. 13.

    Takahashi, Y. et al. Charge-transport in tin iodide perovskite CH3NH3SnI3: origin of high conductivity. Dalton Trans. 40, 5563 (2011).

    Google Scholar 

  14. 14.

    Boyd, C. C., Cheacharoen, R., Leijtens, T. & McGehee, M. D. Understanding degradation mechanisms and improving stability of perovskite photovoltaics. Chem. Rev. 119, 3418–3451 (2019).

    Google Scholar 

  15. 15.

    Grancini, G. et al. One-year stable perovskite solar cells by 2D/3D interface engineering. Nat. Commun. 8, 15684 (2017).

    Google Scholar 

  16. 16.

    Christians, J. A. et al. Tailored interfaces of unencapsulated perovskite solar cells for >1,000 hour operational stability. Nat. Energy 3, 68–74 (2018).

    Google Scholar 

  17. 17.

    Cheacharoen, R. et al. Encapsulating perovskite solar cells to withstand damp heat and thermal cycling. Sustain. Energy Fuels 2, 2398–2406 (2018).

    Google Scholar 

  18. 18.

    Wang, Z. et al. Efficient and ambient-air-stable solar cells with 2D–3D hetero-structured butylammonium–caesium–formamidinium lead halide perovskites. Nat. Energy 2, 17135– (2017).

    Google Scholar 

  19. 19.

    Hou, Y. et al. A generic interface to reduce the efficiency–stability–cost gap of perovskite solar cells. Science 358, 1192–1197 (2017).

    Google Scholar 

  20. 20.

    Marshall, K. P., Walker, M., Walton, R. I. & Hatton, R. A. Enhanced stability and efficiency in hole-transport-layer-free CsSnI3 perovskite photovoltaics. Nat. Energy 1, 1–14 (2016).

    Google Scholar 

  21. 21.

    Gao, W. et al. Robust stability of efficient lead-free formamidinium tin iodide perovskite solar cells realized by structural regulation. J. Phys. Chem. Lett. 9, 6999–7006 (2018).

    Google Scholar 

  22. 22.

    Leijtens, T., Prasanna, R., Gold-Parker, A., Toney, M. F. & McGehee, M. D. Mechanism of tin oxidation and stabilization by lead substitution in tin halide Perovskites. ACS Energy Lett. 2, 2159–2165 (2017).

    Google Scholar 

  23. 23.

    Liao, Y. et al. Highly oriented low-dimensional tin halide perovskites with enhanced stability and photovoltaic performance. J. Am. Chem. Soc. 139, 6693–6699 (2017).

    Google Scholar 

  24. 24.

    Liu, C. et al. C60 additive-assisted crystallization in CH3NH3Pb0.75Sn0.25I3 perovskite solar cells with high stability and efficiency. Nanoscale 9, 13967–13975 (2017).

    Google Scholar 

  25. 25.

    Chi, D. et al. Composition and interface engineering for efficient and thermally stable Pb–Sn mixed low-bandgap perovskite solar cells. Adv. Funct. Mater. 28, 1804603 (2018).

    Google Scholar 

  26. 26.

    Chen, Z. et al. Stable Sn/Pb-based perovskite solar cells with a coherent 2D/3D interface. iScience 9, 337–346 (2018).

    Google Scholar 

  27. 27.

    Holzhey, P. & Saliba, M. A full overview of international standards assessing the long-term stability of perovskite solar cells. J. Mater. Chem. A 6, 21794–21808 (2018).

    Google Scholar 

  28. 28.

    McMeekin, D. P. et al. A mixed-cation lead mixed-halide perovskite absorber for tandem solar cells. Science 351, 151–155 (2016).

    Google Scholar 

  29. 29.

    Turren-Cruz, S. H., Hagfeldt, A. & Saliba, M. Methylammonium-free, high-performance, and stable perovskite solar cells on a planar architecture. Science 362, 449–453 (2018).

    Google Scholar 

  30. 30.

    Tan, W., Bowring, A. R., Meng, A. C., McGehee, M. D. & McIntyre, P. C. Thermal stability of mixed cation metal halide perovskites in air. ACS Appl. Mater. Interfaces 10, 5485–5491 (2018).

    Google Scholar 

  31. 31.

    Bush, K. A. et al. Thermal and environmental stability of semi‐transparent perovskite solar cells for tandems enabled by a solution‐processed nanoparticle buffer layer and sputtered ITO electrode. Adv. Mater. 28, 3937–3943 (2016).

    Google Scholar 

  32. 32.

    Kraut, E. A., Grant, R. W., Waldrop, J. R. & Kowalczyk, S. P. Precise determination of the valence-band edge in X-ray photoemission spectra: application to measurement of semiconductor interface potentials. Phys. Rev. Lett. 44, 1620–1623 (1980).

    Google Scholar 

  33. 33.

    Boyd, C. C. et al. Barrier design to prevent metal-induced degradation and improve thermal stability in perovskite solar cells. ACS Energy Lett. 3, 1772–1778 (2018).

    Google Scholar 

  34. 34.

    Zhao, D. et al. Low-bandgap mixed tin–lead iodide perovskite absorbers with long carrier lifetimes for all-perovskite tandem solar cells. Nat. Energy 2, 17018 (2017).

    Google Scholar 

  35. 35.

    Xiao, Z. et al. Mixed-halide perovskites with stabilized bandgaps. Nano Lett 17, 6863–6869 (2017).

    Google Scholar 

  36. 36.

    Li, W. et al. Subgrain special boundaries in halide perovskite thin films restrict carrier diffusion. ACS Energy Lett. 3, 2669–2670 (2018).

    Google Scholar 

  37. 37.

    Kim, G. Y. et al. Large tunable photoeffect on ion conduction in halide perovskites and implications for photodecomposition. Nat. Mater. 17, 445–449 (2018).

    Google Scholar 

  38. 38.

    Milot, R. L. et al. The effects of doping density and temperature on the optoelectronic properties of formamidinium tin triiodide thin films. Adv. Mater. 30, e1804506 (2018).

    Google Scholar 

  39. 39.

    Domanski, K. et al. Not all that glitters is gold: metal-migration-induced degradation in perovskite solar cells. ACS Nano 10, 6306–6314 (2016).

    Google Scholar 

  40. 40.

    Bush, K. A. et al. 23.6%-efficient monolithic perovskite/silicon tandem solar cells with improved stability. Nat. Energy 2, 17009 (2017).

    Google Scholar 

  41. 41.

    Perkins, C. L. & Hasoon, F. S. Surfactant-assisted growth of CdS thin films for photovoltaic applications. J. Vac. Sci. Technol. A 24, 497–504 (2006).

    Google Scholar 

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This research was supported by the Office of Naval Research award N00014-17-1-2212 and by the US Department of Energy’s Office of Energy Efficiency and Renewable Energy (EERE) under Solar Energy Technologies Office (SETO) agreement no. DE-EE0008551. Work at the Stanford Nano Shared Facilities (SNSF) was supported by the National Science Foundation award ECCS-1542152. S.P.D., M.F.A.M.v.H. and G.T. were supported by the US Department of Energy contract no. DE-AC36-08GO28308 with the Alliance for Sustainable Energy LLC, Manager and Operator of the National Renewable Energy Laboratory (NREL). The authors acknowledge support from the De-risking Halide Perovskite Solar Cells and Combined Characterization projects at NREL, funded by the US Department of Energy, Office of Energy Efficiency and Renewable Energy, Solar Energy Technologies Office. J.J.B. was supported by the Office of Naval Research. We thank S. U. Nanayakkara for performing the atomic force microscopy measurements.

Author information




R.P. and T.L., under the supervision of M.D.M., designed the study. R.P. and T.L. designed the experiments, fabricated solar cells and conducted and interpreted various characterization. S.P.D. and G.T. conducted and interpreted all the XPS measurements. S.P.D., E.J.W., T.L., R.P., J.A.R., G.E.E., S.A.S., J.W., M.F.A.M.v.H., A.F.P. and C.C.B. fabricated devices and/or conducted various stability tests. C.d.P. performed the SEM characterization. R.P. wrote the first draft of the paper. M.D.M., J.J.B. and S.F.B. supervised the work. All the authors contributed to the analysis of the results and revision of the paper.

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Correspondence to Michael D. McGehee.

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T.L. and G.E.E. are co-founders of, and M.D.M. is an advisor to, Swift Solar Inc., a company commercializing perovskite solar cells. All other authors declare no competing interests.

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Supplementary Figs. 1–14, Note 1, Table 1 and ref. 1.

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Prasanna, R., Leijtens, T., Dunfield, S.P. et al. Design of low bandgap tin–lead halide perovskite solar cells to achieve thermal, atmospheric and operational stability. Nat Energy 4, 939–947 (2019).

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