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Top and bottom surfaces limit carrier lifetime in lead iodide perovskite films

Nature Energy volume 2, Article number: 16207 (2017) | Download Citation

Abstract

Carrier recombination at defects is detrimental to the performance of solar energy conversion systems, including solar cells and photoelectrochemical devices. Point defects are localized within the bulk crystal while extended defects occur at surfaces and grain boundaries. If not properly managed, surfaces can be a large source of carrier recombination. Separating surface carrier dynamics from bulk and/or grain-boundary recombination in thin films is challenging. Here, we employ transient reflection spectroscopy to measure the surface carrier dynamics in methylammonium lead iodide perovskite polycrystalline films. We find that surface recombination limits the total carrier lifetime in perovskite polycrystalline thin films, meaning that recombination inside grains and/or at grain boundaries is less important than top and bottom surface recombination. The surface recombination velocity in polycrystalline films is nearly an order of magnitude smaller than that in single crystals, possibly due to unintended surface passivation of the films during synthesis.

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References

  1. 1.

    , ,  & Organometal halide perovskites as visible-light sensitizers for photovoltaic cells. J. Am. Chem. Soc. 131, 6050–6051 (2009).

  2. 2.

    et al. High-performance photovoltaic perovskite layers fabricated through intramolecular exchange. Science 348, 1234–1237 (2015).

  3. 3.

    et al. A molecularly engineered hole-transporting material for efficient perovskite solar cells. Nat. Energy 1, 15017 (2016).

  4. 4.

    et al. Efficient luminescent solar cells based on tailored mixed-cation perovskites. Sci. Adv. 2, e1501170 (2016).

  5. 5.

    , , ,  & High charge carrier mobilities and lifetimes in organolead trihalide perovskites. Adv. Mater. 26, 1584–1589 (2014).

  6. 6.

    et al. Thermally activated exciton dissociation and recombination control the carrier dynamics in organometal halide perovskite. J. Phys. Chem. Lett. 5, 2189–2194 (2014).

  7. 7.

    et al. Electron-hole diffusion lengths exceeding 1 micrometer in an organometal trihalide perovskite absorber. Science 342, 341–344 (2013).

  8. 8.

    et al. Long-range balanced electron- and hole-transport lengths in organic–inorganic CH3NH3PbI3. Science 342, 344–347 (2013).

  9. 9.

    et al. Organometal halide perovskite solar cell materials rationalized: ultrafast charge generation, high and microsecond-long balanced mobilities, and slow recombination. J. Am. Chem. Soc. 136, 5189–5192 (2014).

  10. 10.

    et al. Charge carrier lifetimes exceeding 15 μs in methylammonium lead iodide single crystals. J. Phys. Chem. Lett. 7, 923–928 (2016).

  11. 11.

    et al. Electron-hole diffusion lengths >175 μm in solution-grown CH3NH3PbI3 single crystals. Science 347, 967–970 (2015).

  12. 12.

    et al. Low trap-state density and long carrier diffusion in organolead trihalide perovskite single crystals. Science 347, 519–522 (2015).

  13. 13.

    et al. Intrinsic femtosecond charge generation dynamics in single crystal CH3NH3PbI3. Energy Environ. Sci. 8, 3700–3707 (2015).

  14. 14.

    et al. Enhanced photoluminescence and solar cell performance via lewis base passivation of organic–inorganic lead halide perovskites. ACS Nano 8, 9815–9821 (2014).

  15. 15.

    et al. Impact of microstructure on local carrier lifetime in perovskite solar cells. Science 348, 683–686 (2015).

  16. 16.

    et al. Controllable self-induced passivation of hybrid lead iodide perovskites toward high performance solar cells. Nano Lett. 14, 4158–4163 (2014).

  17. 17.

    et al. Trap states in lead iodide perovskites. J. Am. Chem. Soc. 137, 2089–2096 (2015).

  18. 18.

    et al. Sensitive X-ray detectors made of methylammonium lead tribromide perovskite single crystals. Nat. Photon. 10, 333–339 (2016).

  19. 19.

    , , ,  & Highly narrowband perovskite single-crystal photodetectors enabled by surface-charge recombination. Nat. Photon. 9, 679–686 (2015).

  20. 20.

    et al. Solution-processed hybrid perovskite photodetectors with high detectivity. Nat. Commun. 5, 5404 (2014).

  21. 21.

    et al. Lead halide perovskite nanowire lasers with low lasing thresholds and high quality factors. Nat. Mater. 14, 636–642 (2015).

  22. 22.

    et al. Low-temperature solution-processed wavelength-tunable perovskites for lasing. Nat. Mater. 13, 476–480 (2014).

  23. 23.

    et al. Bright light-emitting diodes based on organometal halide perovskite. Nat. Nanotech. 9, 687–692 (2014).

  24. 24.

    , , ,  & Charge-carrier dynamics in vapour-deposited films of the organolead halide perovskite CH3NH3PbI3−xClx. Energy Environ. Sci. 7, 2269–2275 (2014).

  25. 25.

    et al. Charge-carrier dynamics and mobilities in formamidinium lead mixed-halide perovskites. Adv. Mater. 27, 7938–7944 (2015).

  26. 26.

     & Band filling with free charge carriers in organometal halide perovskites. Nat. Photon. 8, 737–743 (2014).

  27. 27.

    et al. Hot-carrier cooling and photoinduced refractive index changes in organic–inorganic lead halide perovskites. Nat. Commun. 6, 8420 (2015).

  28. 28.

    et al. Comparison of recombination dynamics in CH3NH3PbBr3 and CH3NH3PbI3 perovskite films: influence of exciton binding energy. J. Phys. Chem. Lett. 6, 4688–4692 (2015).

  29. 29.

    et al. Low surface recombination velocity in solution-grown CH3NH3PbBr3 perovskite single crystal. Nat. Commun. 6, 7961 (2015).

  30. 30.

    et al. Mechanism for rapid growth of organic–inorganic halide perovskite crystals. Nat. Commun. 7, 13303 (2016).

  31. 31.

    et al. Square-centimeter solution-processed planar CH3NH3PbI3 perovskite solar cells with efficiency exceeding 15%. Adv. Mater. 27, 6363–6370 (2015).

  32. 32.

    et al. Observation of a hot-phonon bottleneck in lead-iodide perovskites. Nat. Photon. 10, 53–59 (2016).

  33. 33.

    et al. Correlated electron-hole plasma in organometal perovskites. Nat. Commun. 5, 5049 (2014).

  34. 34.

    et al. Direct measurement of the exciton binding energy and effective masses for charge carriers in organic–inorganic tri-halide perovskites. Nat. Phys. 11, 582–587 (2015).

  35. 35.

    ,  & Analysis of multivalley and multibandgap absorption and enhancement of free carriers related to exciton screening in hybrid perovskites. J. Phys. Chem. C 118, 11566–11572 (2014).

  36. 36.

    ,  & Electronic dynamics in natural iron pyrite studied by broadband transient reflection spectroscopy. J. Phys. Chem. C 120, 7736–7747 (2016).

  37. 37.

    et al. Carrier dynamics in 𝛼-Fe2O3 (0001) thin films and single crystals probed by femtosecond transient absorption and reflectivity. J. Appl. Phys. 99, 053521 (2006).

  38. 38.

    et al. Ultrafast pump–probe reflectance spectroscopy: why sodium makes Cu(In,Ga)Se2 solar cells better. Sol. Energy Mater. Sol. Cells 140, 33–37 (2015).

  39. 39.

    et al. Semiconductor interfacial carrier dynamics via photoinduced electric fields. Science 350, 1061–1065 (2015).

  40. 40.

    ,  & Transient photoconductivity in GaAs as measured by time-resolved terahertz spectroscopy. Phys. Rev. B 62, 15764–15777 (2000).

  41. 41.

    , , ,  & Visualizing carrier diffusion in individual single-crystal organolead halide perovskite nanowires and nanoplates. J. Am. Chem. Soc. 137, 12458–12461 (2015).

  42. 42.

    et al. High-quality bulk hybrid perovskite single crystals within minutes by inverse temperature crystallization. Nat. Commun. 6, 8586 (2015).

  43. 43.

    , , ,  & Spatial and temporal imaging of long-range charge transport in perovskite thin films by ultrafast microscopy. Nat. Commun. 6, 7471 (2015).

  44. 44.

    et al. Electron and hole drift mobility measurements on methylammonium lead iodide perovskite solar cells. Appl. Phys. Lett. 108, 173505 (2016).

  45. 45.

    et al. Efficient charge extraction and slow recombination in organic–inorganic perovskites capped with semiconducting single-walled carbon nanotubes. Energy Environ. Sci. 9, 1439–1449 (2016).

  46. 46.

    et al. Self-formed grain boundary healing layer for highly efficient CH3 NH3 PbI3 perovskite solar cells. Nat. Energy 1, 16081 (2016).

  47. 47.

    et al. Unraveling the reasons for efficiency loss in perovskite solar cells. Adv. Funct. Mater. 25, 3925–3933 (2015).

  48. 48.

    , , ,  & Approaching bulk carrier dynamics in organo-halide perovskite nanocrystalline films by surface passivation. J. Phys. Chem. Lett. 7, 1148–1153 (2016).

  49. 49.

    ,  & Preparation of air-stable, low recombination velocity Si(111) surfaces through alkyl termination. Appl. Phys. Lett. 77, 1988–1990 (2000).

  50. 50.

    , , ,  & Unusually low surface recombination and long bulk lifetime in n-CdTe single crystals. Appl. Phys. Lett. 73, 1400–1402 (1998).

  51. 51.

    et al. Determination of CdTe bulk carrier lifetime and interface recombination velocity of CdTe/MgCdTe double heterostructures grown by molecular beam epitaxy. Appl. Phys. Lett. 105, 252101 (2014).

  52. 52.

    Dimensionless solution of the equation describing the effect of surface recombination on carrier decay in semiconductors. J. Appl. Phys. 76, 2851–2854 (1994).

  53. 53.

    et al. Improved air stability of perovskite solar cells via solution-processed metal oxide transport layers. Nat. Nanotech. 11, 75–81 (2016).

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Acknowledgements

K.Z. and M.Y. acknowledge the support by the hybrid perovskite solar cell programme of the National Center for Photovoltaics funded by the US Department of Energy, Office of Energy Efficiency and Renewable Energy, Solar Energy Technologies Office. D.T.M. acknowledges the National Renewable Energy Laboratory Director’s Fellowship. Y.Yang, E.M.M. and M.C.B. acknowledge support from the Solar Photochemistry programme within the US. DOE, Office of Basic Sciences, Office of Science. Work at NREL was conducted under contract number DE-AC36-08G028308.

Author information

Author notes

    • Ye Yang
    •  & Mengjin Yang

    These authors contributed equally to this work.

Affiliations

  1. Chemistry and Nanoscience Center, National Renewable Energy Laboratory, Golden, Colorado 80401, USA

    • Ye Yang
    • , Mengjin Yang
    • , David T. Moore
    • , Yong Yan
    • , Elisa M. Miller
    • , Kai Zhu
    •  & Matthew C. Beard
  2. Department of Chemistry and Environmental Science, New Jersey Institute of Technology, Newark, New Jersey 07102, USA

    • Yong Yan

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Contributions

Y.Yang carried out the transient reflectance experiment; Y.Yang and M.C.B. analysed the data; E.M.M. carried out the XPS data collection and analysis; M.Y. and K.Z. prepared and characterized the thin-film samples; D.T.M. and Y.Yan prepared the single-crystal samples; Y.Yang and M.C.B. wrote the manuscript with input and discussion from all authors.

Competing interests

The authors declare no competing financial interests.

Corresponding authors

Correspondence to Kai Zhu or Matthew C. Beard.

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DOI

https://doi.org/10.1038/nenergy.2016.207

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