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Heterogeneity at multiple length scales in halide perovskite semiconductors

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.

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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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Correspondence to Samuel D. Stranks.

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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). https://doi.org/10.1038/s41578-019-0125-0

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