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The role of Pb oxidation state of the precursor in the formation of 2D perovskite microplates.

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Antony, Leo Sahaya Daphne  ORCID logo
Helmbrecht, Lukas 


Two-dimensional (2D) lead halide perovskites are an exciting class of materials currently being extensively explored for photovoltaics and other optoelectronic applications. Their ionic nature makes them ideal candidates for solution processing into both thin films and nanostructured crystals. Understanding how 2D lead halide perovskite crystals form is key towards full control over their physical properties, which may enable new physical phenomena and devices. Here, we investigate the effects of the Pb oxidation state of the initial inorganic precursor on the growth of pure-phase (n = 1) - Popper 2D perovskite BA2PbI4 in single-step synthesis. We examine the different crystallisation routes in exposing PbO2 and PbI2 powders to a BAI : IPA organo-halide solution, by combining in situ optical microscopy, UV-VIS spectroscopy and time-resolved high performance liquid chromatography. So far, works using PbO2 to synthesise 3D LHPs introduce a preceding step to reduce PbO2 into either PbO or PbI2. In this work, we find that BA2PbI4 is directly formed when exposing PbO2 to BAI : IPA without the need for an external reducing agent. We explain this phenomenon by the spontaneous reduction/oxidation of PbO2/BAI that occurs under iodine-rich conditions. We observe differences in the final morphology (rectangles vs. octagons) and nanocrystal growth rate, which we explain through the different chemistry and iodoplumbate complexes involved in each case. As such, this work spans the horizon of usable lead precursors and offers a new turning knob to control crystal growth in single-step LHP synthesis.


Acknowledgements: This work is part of the Dutch Research Council (NWO) and was performed at the NWO-Institute AMOLF. The authors would like to thank Daniël Koletzki for his contributions in enabling the in situ optical setup. L. S. D. A and E. A. L. acknowledge the D3N project (project no. 17972 of the research programme HTSM2019 from the NWO-TTW Domain), which is (partly) financed by the Dutch Research Council (NWO). S. v. D. acknowledges OCENW.KLEIN.155, which is financed by the Dutch Research Council (NWO). The work of G. G. and J. B. was supported by the EPSRC International Centre to Centre under grant no. EP/S030638/1. A. v. D. W. and W. L. N. acknowledges the Vernieuwingsimpuls Vidi research program “Shaping up materials” with project no. 016.Vidi.189.083, which is partly financed by the Dutch Research Council (NWO). B. E. and I. S. acknowledge OCENW.KLEIN.076, which is financed by the Dutch Research Council (NWO).


3403 Macromolecular and Materials Chemistry, 34 Chemical Sciences, 3406 Physical Chemistry

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Royal Society of Chemistry (RSC)
Nederlandse Organisatie voor Wetenschappelijk Onderzoek (OCENW.KLEIN.155, 016.Vidi.189.083, OCENW.KLEIN.076)
Engineering and Physical Sciences Research Council (EP/S030638/1)
Stichting voor de Technische Wetenschappen (17972)