Heterogeneity at multiple length scales in halide perovskite semiconductors

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Abstract

Materials with highly crystalline lattice structures and low defect concentrations have classically been considered essential for high-performance optoelectronic devices. However, the emergence of high-efficiency devices based on halide perovskites is provoking researchers to rethink this traditional picture, as the heterogeneity in several properties within these materials occurs on a series of length scales. Perovskites are typically fabricated crudely through simple processing techniques, which leads to large local fluctuations in defect density, lattice structure, chemistry and bandgap that appear on short length scales (<100 nm) and across long ranges (>10 μm). Despite these variable and complex non-uniformities, perovskites maintain exceptional device efficiencies and are, as of 2018, the best-performing polycrystalline thin-film solar cell material. In this Review, we highlight the multiple layers of heterogeneity ascertained using high-spatial-resolution methods that provide access to the relevant length scales. We discuss the impact that the optoelectronic variations have on halide perovskite devices, including the prospect that it is this very disorder that leads to their remarkable power-conversion efficiencies.

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Fig. 1: Comparison of the photovoltaic properties of GaAs and perovskite devices.
Fig. 2: The hierarchy of heterogeneity in halide perovskites.
Fig. 3: Nanoscale sub-grain heterogeneity.
Fig. 4: Grain-to-grain heterogeneity.
Fig. 5: Long-range heterogeneity in halide perovskites.
Fig. 6: Roadmap for implementing correlative microscopy for halide perovskites.

References

  1. 1.

    Yu, P. Y. & Cardona, M. in Fundamentals of Semiconductors: Physics and Materials Properties Ch. 4 (Springer, 2010).

  2. 2.

    Pierret, R. F. in Advanced Semiconductor Fundamentals Vol. 6 Ch. 5 (Prentice Hall, 2003).

  3. 3.

    Stoneham, A. M. Non-radiative transitions in semiconductors. Rep. Prog. Phys. 44, 1251 (1981).

  4. 4.

    Queisser, H. J. & Haller, E. E. Defects in semiconductors: some fatal, some vital. Science 281, 945–950 (1998).

  5. 5.

    Childress, L. & Hanson, R. Diamond NV centers for quantum computing and quantum networks. MRS Bull. 38, 134–138 (2013).

  6. 6.

    Monroe, C. Quantum information processing with atoms and photons. Nature 416, 238–246 (2002).

  7. 7.

    National Renewable Energy Laboratory. Best research-cell efficiencies. NREL https://www.nrel.gov/pv/assets/pdfs/best-research-cell-efficiencies-190416.pdf (2019).

  8. 8.

    Wang, F., Bai, S., Tress, W., Hagfeldt, A. & Gao, F. Defects engineering for high-performance perovskite solar cells. NPJ Flex. Electron. 2, 22 (2018).

  9. 9.

    Leijtens, T. et al. Carrier trapping and recombination: the role of defect physics in enhancing the open circuit voltage of metal halide perovskite solar cells. Energy Environ. Sci. 9, 3472–3481 (2016).

  10. 10.

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

  11. 11.

    Brandt, R. E. et al. Searching for “defect-tolerant” photovoltaic materials: combined theoretical and experimental screening. Chem. Mater. 29, 4667–4674 (2017).

  12. 12.

    Agiorgousis, M. L., Sun, Y.-Y., Zeng, H. & Zhang, S. Strong covalency-induced recombination centers in perovskite solar cell material CH3NH3PbI3. J. Am. Chem. Soc. 136, 14570–14575 (2014).

  13. 13.

    Yin, W.-J., Shi, T. & Yan, Y. Unusual defect physics in CH3NH3PbI3 perovskite solar cell absorber. Appl. Phys. Lett. 104, 063903 (2014).

  14. 14.

    Kim, J., Lee, S.-H., Lee, J. H. & Hong, K.-H. The role of intrinsic defects in methylammonium lead iodide perovskite. J. Phys. Chem. Lett. 5, 1312–1317 (2014).

  15. 15.

    Ball, J. M. & Petrozza, A. Defects in perovskite-halides and their effects in solar cells. Nat. Energy 1, 16149 (2016).

  16. 16.

    Yin, W.-J., Shi, T. & Yan, Y. Unique properties of halide perovskites as possible origins of the superior solar cell performance. Adv. Mater. 26, 4653–4658 (2014).

  17. 17.

    Zakutayev, A. et al. Defect tolerant semiconductors for solar energy conversion. J. Phys. Chem. Lett. 5, 1117–1125 (2014).

  18. 18.

    Li, W. et al. Chemically diverse and multifunctional hybrid organic–inorganic perovskites. Nat. Rev. Mater. 2, 16099 (2017). This review discusses the diversity of the perovskite structure and summarizes the wide range of properties that could be promising for different applications.

  19. 19.

    Luo, Y. et al. The relationship between chemical flexibility and nanoscale charge collection in hybrid halide perovskites. Adv. Funct. Mater. 28, 1706995 (2018).

  20. 20.

    Poindexter, J. R. et al. High tolerance to iron contamination in lead halide perovskite solar cells. ACS Nano 11, 7101–7109 (2017).

  21. 21.

    Luo, Y. et al. Spatially heterogeneous chlorine incorporation in organic–inorganic perovskite solar cells. Chem. Mater. 28, 6536–6543 (2016).

  22. 22.

    Abdi-Jalebi, M. et al. Maximizing and stabilizing luminescence from halide perovskites with potassium passivation. Nature 555, 497–501 (2018).

  23. 23.

    Liang, J. et al. Enhancing optical, electronic, crystalline, and morphological properties of cesium lead halide by Mn substitution for high-stability all-inorganic perovskite solar cells with carbon electrodes. Adv. Energy Mater. 8, 1800504 (2018).

  24. 24.

    Saidaminov, M. I. et al. Planar-integrated single-crystalline perovskite photodetectors. Nat. Commun. 6, 8724 (2015).

  25. 25.

    Ran, C., Xu, J., Gao, W., Huang, C. & Dou, S. Defects in metal triiodide perovskite materials towards high-performance solar cells: origin, impact, characterization, and engineering. Chem. Soc. Rev. 47, 4581–4610 (2018).

  26. 26.

    Xing, G. et al. Low-temperature solution-processed wavelength-tunable perovskites for lasing. Nat. Mater. 13, 476–580 (2014).

  27. 27.

    Lee, J. W., Shichijo, H., Tsai, H. L. & Matyi, R. J. Defect reduction by thermal annealing of GaAs layers grown by molecular beam epitaxy on Si substrates. Appl. Phys. Lett. 50, 31–33 (1987).

  28. 28.

    Stranks, S. D. Nonradiative losses in metal halide perovskites. ACS Energy Lett. 2, 1515–1525 (2017). This perspective article assesses the origin of parasitic performance in perovskite solar cells and how to eliminate these factors.

  29. 29.

    Kayes, B. M. et al. 27.6% conversion efficiency, a new record for single-junction solar cells under 1 sun illumination. Presented at the 37th IEEE Photovoltaic Specialists Conference (2011).

  30. 30.

    Jiang, Q. et al. Surface passivation of perovskite film for efficient solar cells. Nat. Photonics 13, 460–466 (2019). This study presents a perovskite solar cell with η = 23.32% and a V oc that is 94.4% of that of the Shockley–Queisser limit.

  31. 31.

    Miller, O. D., Yablonovitch, E. & Kurtz, S. R. Strong internal and external luminescence as solar cells approach the Shockley-Queisser limit. IEEE J. Photovolt. 2, 303–311 (2012).

  32. 32.

    Shockley, W. & Queisser, H. J. Detailed balance limit of efficiency of p-n junction solar cells. J. Appl. Phys. 32, 510–519 (1961).

  33. 33.

    Tennyson, E. M. et al. Nanoimaging of open-circuit voltage in photovoltaic devices. Adv. Energy Mater. 5, 1501142 (2015).

  34. 34.

    Tennyson, E. M. et al. Caesium-incorporated triple cation perovskites deliver fully reversible and stable nanoscale voltage response. ACS Nano 13, 1538–1546 (2019).

  35. 35.

    Rothmann, M. U. et al. Direct observation of intrinsic twin domains in tetragonal CH3NH3PbI3. Nat. Commun. 8, 14547 (2017).

  36. 36.

    McKenna, K. P. Electronic properties of {111} twin boundaries in a mixed-ion lead halide perovskite solar absorber. ACS Energy Lett. 3, 2663–2668 (2018).

  37. 37.

    Liu, Y. et al. Chemical nature of ferroelastic twin domains in CH3NH3PbI3 perovskite. Nat. Mater. 17, 1013–1019 (2018).

  38. 38.

    Jones, T. W. et al. Lattice strain causes non-radiative losses in halide perovskites. Energy Environ. Sci. 12, 596–606 (2019). This study provides experimental evidence to suggest that strain is formed in a perovskite film during fabrication and demonstrates this effect at multiple length scales.

  39. 39.

    Phung, N. & Abate, A. The impact of nano- and microstructure on the stability of perovskite solar cells. Small 14, 1802573 (2018).

  40. 40.

    Howard, J. M. et al. Humidity-induced photoluminescence hysteresis in variable Cs/Br ratio hybrid perovskites. J. Phys. Chem. Lett. 9, 3463–3469 (2018).

  41. 41.

    Howard, J. M., Tennyson, E. M., Neves, B. R. & Leite, M. S. Machine learning for perovskites’ reap-rest-recovery cycle. Joule 3, 325–337 (2018).

  42. 42.

    Saliba, M., Correa-Baena, J. P., Gratzel, M., Hagfeldt, A. & Abate, A. Perovskite solar cells: from the atomic level to film quality and device performance. Angew. Chem. Int. Ed. 57, 2554–2569 (2018).

  43. 43.

    Roose, B., Wang, Q. & Abate, A. The role of charge selective contacts in perovskite solar cell stability. Adv. Energy Mater. 9, 1803140 (2018).

  44. 44.

    Bercegol, A. et al. Spatial inhomogeneity analysis of cesium-rich wrinkles in triple-cation perovskite. J. Phys. Chem. C 122, 23345–23351 (2018).

  45. 45.

    Bush, K. A. et al. Controlling thin-film stress and wrinkling during perovskite film formation. ACS Energy Lett. 3, 1225–1232 (2018).

  46. 46.

    Weber, S. A. L. et al. How the formation of interfacial charge causes hysteresis in perovskite solar cells. Energy Environ. Sci. 11, 2404–2413 (2018).

  47. 47.

    Bi, D. et al. Polymer-templated nucleation and crystal growth of perovskite films for solar cells with efficiency greater than 21%. Nat. Energy 1, 16142 (2016).

  48. 48.

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

  49. 49.

    Tidhar, Y. et al. Crystallization of methyl ammonium lead halide perovskites: implications for photovoltaic applications. J. Am. Chem. Soc. 136, 13249–13256 (2014).

  50. 50.

    Eperon, G. E. et al. The importance of moisture in hybrid lead halide perovskite thin film fabrication. ACS Nano 9, 9380–9393 (2015).

  51. 51.

    Gao, H. et al. Nucleation and crystal growth of organic–inorganic lead halide perovskites under different relative humidity. ACS Appl. Mater. Interfaces 7, 9110–9117 (2015).

  52. 52.

    Rothmann, M. U. et al. Structural and chemical changes to CH3NH3PbI3 induced by electron and gallium ion beams. Adv. Mater. 30, 1800629 (2018).

  53. 53.

    Tian, W. et al. Limiting perovskite solar cell performance by heterogeneous carrier extraction. Angew. Chem. Int. Ed. 55, 13067–13071 (2016).

  54. 54.

    Zong, Y. et al. Continuous grain-boundary functionalization for high-efficiency perovskite solar cells with exceptional stability. Chem 4, 1404–1415 (2018).

  55. 55.

    Park, B.-w et al. Understanding how excess lead iodide precursor improves halide perovskite solar cell performance. Nat. Commun. 9, 3301 (2018).

  56. 56.

    Kosasih, F. U. & Ducati, C. Characterising degradation of perovskite solar cells through in-situ and operando electron microscopy. Nano Energy 47, 243–256 (2018).

  57. 57.

    Tian, Y. et al. Enhanced organo-metal halide perovskite photoluminescence from nanosized defect-free crystallites and emitting sites. J. Phys. Chem. Lett. 6, 4171–4177 (2015).

  58. 58.

    Zhou, Y., Sternlicht, H. & Padture, N. P. Transmission electron microscopy of halide perovskite materials and devices. Joule 3, 641–661 (2019).

  59. 59.

    Correa-Baena, J.-P. et al. Homogenized halides and alkali cation segregation in alloyed organic-inorganic perovskites. Science 363, 627–631 (2019). Study in which the chemical signatures of elements in the perovskite structure are imaged with nanometre resolution and related to solar cell performance.

  60. 60.

    Leblebici, S. Y. et al. Facet-dependent photovoltaic efficiency variations in single grains of hybrid halide perovskite. Nat. Energy 1, 16093 (2016).

  61. 61.

    Eperon, G. E., Moerman, D. & Ginger, D. S. Anticorrelation between local photoluminescence and photocurrent suggests variability in contact to active layer in perovskite solar cells. ACS Nano 10, 10258–10266 (2016).

  62. 62.

    Parsons, S. Introduction to twinning. Acta Crystallogr. D 59, 1995–2003 (2003).

  63. 63.

    Strelcov, E. et al. CH3NH3PbI3 perovskites: ferroelasticity revealed. Sci. Adv. 3, e1602165 (2017).

  64. 64.

    Rakita, Y. et al. Tetragonal CH3NH3PbI3 is ferroelectric. Proc. Natl Acad. Sci. USA 114, E5504–E5512 (2017).

  65. 65.

    Egger, D. A. et al. What remains unexplained about the properties of halide perovskites? Adv. Mater. 30, 1800691 (2018).

  66. 66.

    Zhang, D. et al. Atomic-resolution transmission electron microscopy of electron beam–sensitive crystalline materials. Science 359, 675–679 (2018).

  67. 67.

    Chen, S. et al. Atomic scale insights into structure instability and decomposition pathway of methylammonium lead iodide perovskite. Nat. Commun. 9, 4807 (2018).

  68. 68.

    Egerton, R. F. Mechanisms of radiation damage in beam-sensitive specimens, for TEM accelerating voltages between 10 and 300 kV. Microsc. Res. Tech. 75, 1550–1556 (2012).

  69. 69.

    Milosavljevic, A. R., Huang, W., Sadhu, S. & Ptasinska, S. Low-energy electron-induced transformations in organolead halide perovskite. Angew. Chem. Int. Ed. 55, 10083–10087 (2016).

  70. 70.

    Klein-Kedem, N., Cahen, D. & Hodes, G. Effects of light and electron beam irradiation on halide perovskites and their solar cells. Acc. Chem. Res. 49, 347–354 (2016).

  71. 71.

    Frost, J. M. et al. Atomistic origins of high-performance in hybrid halide perovskite solar cells. Nano Lett. 14, 2584–2590 (2014).

  72. 72.

    Frost, J. M., Butler, K. T. & Walsh, A. Molecular ferroelectric contributions to anomalous hysteresis in hybrid perovskite solar cells. Appl. Phys. Lett. 2, 081506 (2014).

  73. 73.

    Wei, J. et al. Hysteresis analysis based on the ferroelectric effect in hybrid perovskite solar cells. J. Phys. Chem. Lett. 5, 3937–3945 (2014).

  74. 74.

    Garten, L. M. et al. The existence and impact of persistent ferroelectric domains in MAPbI3. Sci. Adv. 5, eaas9311 (2019).

  75. 75.

    Salje, E. K. H. Ferroelastic materials. Ann. Rev. Mater. Res. 42, 265–283 (2012).

  76. 76.

    deQuilettes, D. W. et al. Impact of microstructure on local carrier lifetime in perovskite solar cells. Science 348, 683–686 (2015). A pioneering study showing that individual grains in the halide perovskite microstructure have heterogeneous emission intensities and lifetimes.

  77. 77.

    deQuilettes, D. W. et al. Tracking photoexcited carriers in hybrid perovskite semiconductors: trap-dominated spatial heterogeneity and diffusion. ACS Nano 11, 11488–11496 (2017).

  78. 78.

    Yang, M. et al. Do grain boundaries dominate non-radiative recombination in CH3NH3PbI3 perovskite thin films? Phys. Chem. Chem. Phys. 19, 5043–5050 (2017).

  79. 79.

    Zhou, Y., Game, O. S., Pang, S. & Padture, N. P. Microstructures of organometal trihalide perovskites for solar cells: their evolution from solutions and characterization. J. Phys. Chem. Lett. 6, 4827–4839 (2015).

  80. 80.

    Khassaf, H., Yadavalli, S. K., Zhou, Y., Padture, N. P. & Kingon, A. I. Effect of grain boundaries on charge transport in methylammonium lead iodide perovskite thin films. J. Phys. Chem. C 123, 5321–5325 (2019).

  81. 81.

    Adhyaksa, G. W. P. et al. Understanding detrimental and beneficial grain boundary effects in halide perovskites. Adv. Mater. 30, 1804792 (2018).

  82. 82.

    Giesbrecht, N. et al. Synthesis of perfectly oriented and micrometer-sized MAPbBr3 perovskite crystals for thin-film photovoltaic applications. ACS Energy Lett. 1, 150–154 (2016).

  83. 83.

    Xing, J. et al. High-efficiency light-emitting diodes of organometal halide perovskite amorphous nanoparticles. ACS Nano 10, 6623–6630 (2016).

  84. 84.

    Wang, J. et al. Reducing surface recombination velocities at the electrical contacts will improve perovskite photovoltaics. ACS Energy Lett. 4, 222–227 (2019).

  85. 85.

    Reid, O. G., Yang, M., Kopidakis, N., Zhu, K. & Rumbles, G. Grain-size-limited mobility in methylammonium lead iodide perovskite thin films. ACS Energy Lett. 1, 561–565 (2016).

  86. 86.

    Edri, E. et al. Elucidating the charge carrier separation and working mechanism of CH3NH3PbI3−xClx perovskite solar cells. Nat. Commun. 5, 3461 (2014).

  87. 87.

    Barnard, E. S. et al. 3D lifetime tomography reveals how CdCl2 improves recombination throughout CdTe solar cells. Adv. Mater. 29, 1603801 (2016).

  88. 88.

    Ono, L. K. & Qi, Y. Surface and interface aspects of organometal halide perovskite materials and solar cells. J. Phys. Chem. Lett. 7, 4764–4794 (2016).

  89. 89.

    Brenner, T. M., Egger, D. A., Kronik, L., Hodes, G. & Cahen, D. Hybrid organic–inorganic perovskites: low-cost semiconductors with intriguing charge-transport properties. Nat. Rev. Mater. 1, 15007 (2016).

  90. 90.

    Walsh, A. & Stranks, S. D. Taking control of ion transport in halide perovskite solar cells. ACS Energy Lett. 3, 1983–1990 (2018). This article summarizes the fundamentals of both internal and external triggers for ionic transport in halide perovskite solar cells.

  91. 91.

    Stavrakas, C. et al. Probing buried recombination pathways in perovskite structures using 3D photoluminescence tomography. Energy Environ. Sci. 11, 2846–2852 (2018).

  92. 92.

    Ahn, N. et al. Trapped charge-driven degradation of perovskite solar cells. Nat. Commun. 7, 13422 (2016).

  93. 93.

    Yoon, S. J., Kuno, M. & Kamat, P. V. Shift happens. How halide ion defects influence photoinduced segregation in mixed halide perovskites. ACS Energy Lett. 2, 1507–1514 (2017).

  94. 94.

    Brennan, M. C., Draguta, S., Kamat, P. V. & Kuno, M. Light-induced anion phase segregation in mixed halide perovskites. ACS Energy Lett. 3, 204–213 (2018).

  95. 95.

    Noh, J. H., Im, S. H., Heo, J. H., Mandal, T. N. & Seok, S. I. Chemical management for colorful, efficient, and stable inorganic–organic hybrid nanostructured solar cells. Nano Lett. 13, 1764–1769 (2013).

  96. 96.

    Jesper Jacobsson, T. et al. Exploration of the compositional space for mixed lead halogen perovskites for high efficiency solar cells. Energy Environ. Sci. 9, 1706–1724 (2016).

  97. 97.

    Gratia, P. et al. Intrinsic halide segregation at nanometer scale determines the high efficiency of mixed cation/mixed halide perovskite solar cells. J. Am. Chem. Soc. 138, 15821–15824 (2016).

  98. 98.

    Song, T.-B., Sharp, I. D. & Sutter-Fella, C. M. Understanding macroscale functionality of metal halide perovskites in terms of nanoscale heterogeneities. J. Phys. Energy 1, 011002 (2018).

  99. 99.

    Dou, L. et al. Spatially resolved multicolor CsPbX3 nanowire heterojunctions via anion exchange. Proc. Natl Acad. Sci. USA 114, 7216–7221 (2017).

  100. 100.

    Dar, M. I. et al. Asymmetric cathodoluminescence emission in CH3NH3PbI3−xBrx perovskite single crystals. ACS Photon. 3, 947–952 (2016).

  101. 101.

    Hentz, O., Zhao, Z. & Gradecak, S. Impacts of ion segregation on local optical properties in mixed halide perovskite films. Nano Lett. 16, 1485–1490 (2016).

  102. 102.

    Li, W. et al. Phase segregation enhanced ion movement in efficient inorganic CsPbIBr2 solar cells. Adv. Energy Mater. 7, 1700946 (2017).

  103. 103.

    Kulbak, M. et al. Cesium enhances long-term stability of lead bromide perovskite-based solar cells. J. Phys. Chem. Lett. 7, 167–172 (2016).

  104. 104.

    Hoke, E. T. et al. Reversible photo-induced trap formation in mixed-halide hybrid perovskites for photovoltaics. Chem. Sci. 6, 613–617 (2015). The first study to experimentally demonstrate light-activated halide ion migration for perovskites with a mixed-halide (I and Br ) composition.

  105. 105.

    Edri, E. et al. Why lead methylammonium tri-Iodide perovskite-based solar cells require a mesoporous electron transporting scaffold (but not necessarily a hole conductor). Nano Lett. 14, 1000–1004 (2014).

  106. 106.

    Stranks, S. D. et al. Recombination kinetics in organic-inorganic perovskites: excitons, free charge, and subgap states. Phys. Rev. Appl. 2, 034007 (2014).

  107. 107.

    Stranks, S. D., Hoye, R. L. Z., Di, D., Friend, R. H. & Deschler, F. The physics of light emission in halide perovskite devices. Adv. Mater. 1803336 (2019).

  108. 108.

    Kovalenko, M. V., Protesescu, L. & Bodnarchuk, M. I. Properties and potential optoelectronic applications of lead halide perovskite nanocrystals. Science 358, 745–750 (2017).

  109. 109.

    El-Hajje, G. et al. Quantification of spatial inhomogeneity in perovskite solar cells by hyperspectral luminescence imaging. Energy Environ. Sci. 9, 2286–2294 (2016).

  110. 110.

    Xiao, M. et al. A fast deposition-crystallization procedure for highly efficient lead iodide perovskite thin-film solar cells. Angew. Chem. 126, 10056–10061 (2014).

  111. 111.

    Cho, N. et al. Pure crystal orientation and anisotropic charge transport in large-area hybrid perovskite films. Nat. Commun. 7, 13407 (2016).

  112. 112.

    Kim, D. H. et al. 300% Enhancement of carrier mobility in uniaxial-oriented perovskite films formed by topotactic-oriented attachment. Adv. Mater. 29, 1606831 (2017).

  113. 113.

    Kim, M. K. et al. Effective control of crystal grain size in CH3NH3PbI3 perovskite solar cells with a pseudohalide Pb(SCN)2 additive. CrystEngComm 18, 6090–6095 (2016).

  114. 114.

    Kim, W. et al. Oriented grains with preferred low-angle grain boundaries in halide perovskite films by pressure-induced crystallization. Adv. Energy Mater. 8, 1702369 (2018).

  115. 115.

    Li, W., Fan, J., Mai, Y. & Wang, L. Aquointermediate assisted highly orientated perovskite thin films toward thermally stable and efficient solar cells. Adv. Energy Mater. 7, 1601433 (2017).

  116. 116.

    Nie, W. et al. High-efficiency solution-processed perovskite solar cells with millimeter-scale grains. Science 347, 522–525 (2015).

  117. 117.

    Sun, Y., Peng, J., Chen, Y., Yao, Y. & Liang, Z. Triple-cation mixed-halide perovskites: towards efficient, annealing-free and air-stable solar cells enabled by Pb(SCN)2 additive. Sci. Rep. 7, 46193 (2017).

  118. 118.

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

  119. 119.

    Tress, W. et al. Predicting the open-circuit voltage of CH3NH3PbI3 perovskite solar cells using electroluminescence and photovoltaic quantum efficiency spectra: The role of radiative and non-radiative recombination. Adv. Energy Mater. 5, 1400812 (2015).

  120. 120.

    Tvingstedt, K. et al. Radiative efficiency of lead iodide based perovskite solar cells. Sci. Rep. 4, 6071 (2014).

  121. 121.

    Würfel, P., Finkbeiner, S. & Daub, E. Generalized Planck’s radiation law for luminescence via indirect transitions. Appl. Phys. A 60, 67–70 (1995).

  122. 122.

    Stolterfoht, M. et al. Visualization and suppression of interfacial recombination for high-efficiency large-area pin perovskite solar cells. Nat. Energy 3, 847–854 (2018).

  123. 123.

    Zhao, J. et al. Strained hybrid perovskite thin films and their impact on the intrinsic stability of perovskite solar cells. Sci. Adv. 3, eaao5616 (2017).

  124. 124.

    Wang, J. T.-W. et al. Efficient perovskite solar cells by metal ion doping. Energy Environ. Sci. 9, 2892–2901 (2016).

  125. 125.

    Lilliu, S. et al. Mapping morphological and structural properties of lead halide perovskites by scanning nanofocus XRD. Adv. Funct. Mater. 26, 8221–8230 (2016).

  126. 126.

    Saliba, M. et al. Cesium-containing triple cation perovskite solar cells: improved stability, reproducibility and high efficiency. Energy Environ. Sci. 9, 1989–1997 (2016). The first study to incorporate Cs + into the halide perovskite lattice by partially substituting the organic FA + and MA + cations, leading to an increase in performance and stability.

  127. 127.

    Akkerman, Q. A. et al. Solution synthesis approach to colloidal cesium lead halide perovskite nanoplatelets with monolayer-level thickness control. J. Am. Chem. Soc. 138, 1010–1016 (2016).

  128. 128.

    Chu, Z. et al. Impact of grain boundaries on efficiency and stability of organic-inorganic trihalide perovskites. Nat. Commun. 8, 2230 (2017).

  129. 129.

    Li, T. et al. Additive engineering for highly efficient organic–inorganic halide perovskite solar cells: recent advances and perspectives. J. Mater. Chem. A 5, 12602–12652 (2017).

  130. 130.

    Zhao, Y. et al. Perovskite seeding growth of formamidinium-lead-iodide-based perovskites for efficient and stable solar cells. Nat. Commun. 9, 1607 (2018).

  131. 131.

    Pathoor, N. et al. Fluorescence blinking beyond nanoconfinement: spatially synchronous intermittency of entire perovskite microcrystals. Angew. Chem. Int. Ed. 57, 11603–11607 (2018).

  132. 132.

    Moerman, D., Eperon, G. E., Precht, J. T. & Ginger, D. S. Correlating photoluminescence heterogeneity with local electronic properties in methylammonium lead tribromide perovskite thin films. Chem. Mater. 29, 5484–5492 (2017).

  133. 133.

    Tian, Y. et al. Giant photoluminescence blinking of perovskite nanocrystals reveals single-trap control of luminescence. Nano Lett. 15, 1603–1608 (2015).

  134. 134.

    Merdasa, A. et al. “Supertrap” at work: extremely efficient nonradiative recombination channels in MAPbI3 perovskites revealed by luminescence super-resolution imaging and spectroscopy. ACS Nano 11, 5391–5404 (2017).

  135. 135.

    Gagliardi, A. & Abate, A. Mesoporous electron-selective contacts enhance the tolerance to interfacial ion accumulation in perovskite solar cells. ACS Energy Lett. 3, 163–169 (2018).

  136. 136.

    Ravishankar, S. et al. Influence of charge transport layers on open-circuit voltage and hysteresis in perovskite solar cells. Joule 2, 788–798 (2018).

  137. 137.

    Simpson, M. J., Doughty, B., Yang, B., Xiao, K. & Ma, Y.-Z. Spatial localization of excitons and charge carriers in hybrid perovskite thin films. J. Phys. Chem. Lett. 6, 3041–3047 (2015).

  138. 138.

    Pazos-Outón, L. M. et al. Photon recycling in lead iodide perovskite solar cells. Science 351, 1430–1433 (2016).

  139. 139.

    Dursun, I. et al. Efficient photon recycling and radiation trapping in cesium lead halide perovskite waveguides. ACS Energy Lett. 3, 1492–1498 (2018).

  140. 140.

    Shimamura, K., Yuan, Z., Shimojo, F. & Nakano, A. Effects of twins on the electronic properties of GaAs. Appl. Phys. Lett. 103, 022105 (2013).

  141. 141.

    Garrett, J. L. et al. Real-time nanoscale open-circuit voltage dynamics of perovskite solar cells. Nano Lett. 17, 2554–2560 (2017).

  142. 142.

    Jariwala, S. et al. Imaging grain structure in halide perovskites: local crystal misorientation influences non-radiative recombination. Preprint at arXiv https://arxiv.org/abs/1903.11033 (2019).

  143. 143.

    Calais, E. et al. Tectonic strain in plate interiors? Nature 438, E9–E10 (2005).

  144. 144.

    Tsai, H. et al. Light-induced lattice expansion leads to high-efficiency perovskite solar cells. Science 360, 67–70 (2018).

  145. 145.

    Vrucinic, M. et al. Local versus long-range diffusion effects of photoexcited states on radiative recombination in organic–inorganic lead halide perovskites. Adv. Sci. 2, 1500136 (2015).

  146. 146.

    Kutes, Y. et al. Mapping the photoresponse of CH3NH3PbI3 hybrid perovskite thin films at the nanoscale. Nano Lett. 16, 3434–3441 (2016).

  147. 147.

    Bergmann, V. W. et al. Real-space observation of unbalanced charge distribution inside a perovskite-sensitized solar cell. Nat. Commun. 5, 5001 (2014).

  148. 148.

    deQuilettes, D. W. et al. Photo-induced halide redistribution in organic-inorganic perovskite films. Nat. Commun. 7, 11683 (2016).

  149. 149.

    Draguta, S. et al. Rationalizing the light-induced phase separation of mixed halide organic–inorganic perovskites. Nat. Commun. 8, 200 (2017).

  150. 150.

    Nie, W. et al. Light-activated photocurrent degradation and self-healing in perovskite solar cells. Nat. Commun. 7, 11574 (2016).

  151. 151.

    Gottesman, R. et al. Extremely slow photoconductivity response of CH3NH3PbI3 perovskites suggesting structural changes under working conditions. J. Phys. Chem. Lett. 5, 2662–2669 (2014).

  152. 152.

    Barker, A. J. et al. Defect-assisted photoinduced halide segregation in mixed-halide perovskite thin films. ACS Energy Lett. 2, 1416–1424 (2017).

  153. 153.

    Nickel, N. H., Lang, F., Brus, V. V., Shargaieva, O. & Rappich, J. Unraveling the light-induced degradation mechanisms of CH3NH3PbI3 perovskite films. Adv. Electron. Mater. 3, 1700158 (2017).

  154. 154.

    Bischak, C. G. et al. Origin of reversible photoinduced phase separation in hybrid perovskites. Nano Lett. 17, 1028–1033 (2017).

  155. 155.

    Xu, R.-P. et al. In situ observation of light illumination-induced degradation in organometal mixed-halide perovskite films. ACS Appl. Mater. Interfaces 10, 6737–6746 (2018).

  156. 156.

    Liu, Z. et al. Open-circuit voltages exceeding 1.26 V in planar methylammonium lead iodide perovskite solar cells. ACS Energy Lett. 4, 110–117 (2018).

  157. 157.

    Chen, S. et al. Light illumination induced photoluminescence enhancement and quenching in lead halide perovskite. Solar RRL 1, 1600001 (2017).

  158. 158.

    Brenes, R., Eames, C., Bulovic, V., Islam, M. S. & Stranks, S. D. The impact of atmosphere on the local luminescence properties of metal halide perovskite grains. Adv. Mater. 30, 1706208 (2018).

  159. 159.

    Tennyson, E. M., Howard, J. M. & Leite, M. S. Mesoscale functional imaging of materials for photovoltaics. ACS Energy Lett. 2, 1825–1834 (2017). A perspective highlighting the future of functional and correlative imaging techniques and reviewing popular methods used to observe mesoscale (5–50 nm) heterogeneity in solar cells.

  160. 160.

    Li, X. et al. Improved performance and stability of perovskite solar cells by crystal crosslinking with alkylphosphonic acid ω-ammonium chlorides. Nat. Chem. 7, 703–711 (2015).

  161. 161.

    Bischak, C. G., Sanehira, E. M., Precht, J. T., Luther, J. M. & Ginsberg, N. S. Heterogeneous charge carrier dynamics in organic–inorganic hybrid materials: nanoscale lateral and depth-dependent variation of recombination rates in methylammonium lead halide perovskite thin films. Nano Lett. 15, 4799–4807 (2015).

  162. 162.

    Osherov, A. et al. The impact of phase retention on the structural and optoelectronic properties of metal halide perovskites. Adv. Mater. 28, 10757–10763 (2016).

  163. 163.

    Galkowski, K. et al. Spatially resolved studies of the phases and morphology of methylammonium and formamidinium lead tri-halide perovskites. Nanoscale 9, 3222–3230 (2017).

  164. 164.

    Soufiani, A. M. et al. Impact of microstructure on the electron–hole interaction in lead halide perovskites. Energy Environ. Sci. 10, 1358–1366 (2017).

  165. 165.

    Divitini, G. et al. In situ observation of heat-induced degradation of perovskite solar cells. Nat. Energy 1, 15012 (2016).

  166. 166.

    Collins, L. et al. Breaking the time barrier in Kelvin probe force microscopy: fast free force reconstruction using the g-mode platform. ACS Nano 11, 8717–8729 (2017).

  167. 167.

    Kutes, Y. et al. Direct observation of ferroelectric domains in solution-processed CH3NH3PbI3 perovskite thin films. J. Phys. Chem. Lett. 5, 3335–3339 (2014).

  168. 168.

    Chen, B. et al. Imaging spatial variations of optical bandgaps in perovskite solar cells. Adv. Energy Mater. 0, 1802790 (2018).

  169. 169.

    Song, Z. et al. Perovskite solar cell stability in humid air: partially reversible phase transitions in the PbI2-CH3NH3I-H2O system. Adv. Energy Mater. 6, 1600846 (2016).

  170. 170.

    Harvey, S. P. et al. Probing perovskite inhomogeneity beyond the surface: TOF-SIMS analysis of halide perovskite photovoltaic devices. ACS Appl. Mater. Interfaces 10, 28541–28552 (2018).

  171. 171.

    Quintero-Bermudez, R. et al. Compositional and orientational control in metal halide perovskites of reduced dimensionality. Nat. Mater. 17, 900–907 (2018).

  172. 172.

    Brenes, R. et al. Metal halide perovskite polycrystalline films exhibiting properties of single crystals. Joule 1, 155–167 (2017).

  173. 173.

    Anaya, M., Galisteo-López, J. F., Calvo, M. E., Espinós, J. P. & Míguez, H. Origin of light-induced photophysical effects in organic metal halide perovskites in the presence of oxygen. J. Phys. Chem. Lett. 9, 3891–3896 (2018).

  174. 174.

    Tian, Y. et al. Mechanistic insights into perovskite photoluminescence enhancement: light curing with oxygen can boost yield thousandfold. Phys. Chem. Chem. Phys. 17, 24978–24987 (2015).

  175. 175.

    Midgley, P. & Johnstone, D. Scanning electron diffraction — crystal mapping at the nanoscale. Microsc. Microanal. 24, 182–183 (2018).

  176. 176.

    de la Pena, F. et al. Electron microscopy (big and small) data analysis with the open source software package HyperSpy. Microsc. Microanal. 23, 214–215 (2017).

  177. 177.

    Johnstone, D. N. et al. pyxem/pyxem: pyXem 0.7.1. Zenodo https://doi.org/10.5281/zenodo.2650296 (2019).

  178. 178.

    Butler, K. T., Davies, D. W., Cartwright, H., Isayev, O. & Walsh, A. Machine learning for molecular and materials science. Nature 559, 547–555 (2018).

  179. 179.

    Borodinov, N. et al. Deep neural networks for understanding noisy data applied to physical property extraction in scanning probe microscopy. NPJ Comput. Mater. 5, 25 (2019).

  180. 180.

    Cacovich, S. et al. Unveiling the chemical composition of halide perovskite films using multivariate statistical analyses. ACS Appl. Energy Mater. 12, 7174–7181 (2018).

  181. 181.

    Martineau, B. H., Johnstone, D. N., van Helvoort, A. T. J., Midgley, P. A. & Eggeman, A. S. Unsupervised machine learning applied to scanning precession electron diffraction data. Adv. Struct. Chem. Imaging 5, 3 (2019).

  182. 182.

    Zhang, Y. et al. Machine learning in electronic-quantum-matter imaging experiments. Nature 570, 484–490 (2019).

  183. 183.

    Grancini, G. et al. CH3NH3PbI3 perovskite single crystals: surface photophysics and their interaction with the environment. Chem. Sci. 6, 7305–7310 (2015).

  184. 184.

    Huang, J., Shao, Y. & Dong, Q. Organometal trihalide perovskite single crystals: a next wave of materials for 25% efficiency photovoltaics and applications beyond? J. Phys. Chem. Lett. 6, 3218–3227 (2015).

  185. 185.

    Rolston, N. et al. Engineering stress in perovskite solar cells to improve stability. Adv. Energy Mater. 8, 1802139 (2018).

  186. 186.

    Li, X., Luo, Y., Holt, M. V., Cai, Z. & Fenning, D. P. Residual nanoscale strain in cesium lead bromide perovskite reduces stability and shifts local luminescence. Chem. Mater. 31, 2778–2785 (2019).

  187. 187.

    Shi, H. & Du, M.-H. Shallow halogen vacancies in halide optoelectronic materials. Phys. Rev. B 90, 174103 (2014).

  188. 188.

    Lai, M. et al. Intrinsic anion diffusivity in lead halide perovskites is facilitated by a soft lattice. Proc. Natl Acad. Sci. USA 115, 11929–11934 (2018).

  189. 189.

    Rajagopal, A., Stoddard, R. J., Jo, S. B., Hillhouse, H. W. & Jen, A. K. Y. Overcoming the photovoltage plateau in large bandgap perovskite photovoltaics. Nano Lett. 18, 3985–3993 (2018).

  190. 190.

    Stoddard, R. J. et al. Enhancing defect tolerance and phase stability of high-bandgap perovskites via guanidinium alloying. ACS Energy Lett. 3, 1261–1268 (2018).

  191. 191.

    Yang, W. S. et al. Iodide management in formamidinium-lead-halide–based perovskite layers for efficient solar cells. Science 356, 1376–1379 (2017).

  192. 192.

    Li, B. et al. Surface passivation engineering strategy to fully-inorganic cubic CsPbI3 perovskites for high-performance solar cells. Nat. Commun. 9, 1076 (2018).

  193. 193.

    Zhang, W. et al. Enhanced optoelectronic quality of perovskite thin films with hypophosphorous acid for planar heterojunction solar cells. Nat. Commun. 6, 10030 (2015).

  194. 194.

    Zhu, C. et al. Strain engineering in perovskite solar cells and its impacts on carrier dynamics. Nat. Commun. 10, 815 (2019).

  195. 195.

    Hou, Q. et al. Back-contact perovskite solar cells with honeycomb-like charge collecting electrodes. Nano Energy 50, 710–716 (2018).

  196. 196.

    Lin, X. et al. Effect of grain cluster size on back-contact perovskite solar cells. Adv. Funct. Mater. 28, 1805098 (2018).

  197. 197.

    Stranks, S. D. & Plochocka, P. The influence of the Rashba effect. Nat. Mater. 17, 381–382 (2018).

  198. 198.

    Kim, M., Im, J., Freeman, A. J., Ihm, J. & Jin, H. Switchable S = 1/2 and J = 1/2 Rashba bands in ferroelectric halide perovskites. Proc. Natl Acad. Sci. USA 111, 6900–6904 (2014).

  199. 199.

    Yang, M.-M., Kim, D. J. & Alexe, M. Flexo-photovoltaic effect. Science 360, 904–907 (2018).

  200. 200.

    Faber, T. E. & Ziman, J. M. A theory of the electrical properties of liquid metals. Philos. Mag. 11, 153–173 (1965).

  201. 201.

    Guo, Y. et al. Dynamic emission Stokes shift and liquid-like dielectric solvation of band edge carriers in lead-halide perovskites. Nat. Commun. 10, 1175 (2019).

  202. 202.

    Zhu, H. et al. Screening in crystalline liquids protects energetic carriers in hybrid perovskites. Science 353, 1409–1413 (2016).

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Acknowledgements

E.M.T. acknowledges funding from the UK Engineering and Physical Sciences Research Council under grant reference EP/R023980/1. T.A.S.D. acknowledges support from a National University of Ireland Travelling Studentship. S.D.S. acknowledges the Royal Society and Tata Group (UF150033). The work has received funding from the European Research Council under the European Union’s Horizon 2020 research and innovation programme (HYPERION, grant agreement no. 756962). The authors gratefully acknowledge the helpful discussions with S. Macpherson, J. M. Howard, G. Hodes, D. Cahen and D. N. Johnstone. The authors also thank Diamond Light Source for access and support in the use of the electron Physical Science Imaging Centre (instrument E02 and proposal numbers EM19793-1 and EM19793-2) that contributed to the data presented here.

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All authors contributed equally to the preparation of this manuscript.

Correspondence to Samuel D. Stranks.

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Competing interests

S.D.S. is a co-founder of Swift Solar, a company commercializing high-power, lightweight perovskite solar panels. E.M.T. and T.A.S.D. declare no competing interests.

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Tennyson, E.M., Doherty, T.A.S. & Stranks, S.D. Heterogeneity at multiple length scales in halide perovskite semiconductors. Nat Rev Mater 4, 573–587 (2019) doi:10.1038/s41578-019-0125-0

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