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|Title:||Self-assembly of a robust hydrogen-bonded octylphosphonate network on cesium lead bromide perovskite nanocrystals for light-emitting diodes||Authors:||Brown, Alasdair Angus Macintyre
Hooper, Thomas J. N.
Veldhuis, Sjoerd Antonius
Chin, Xin Yu
Tey, Ju Nie
Pu, Suan Hui
Subodh Gautam Mhaisalkar
|Keywords:||Engineering::Materials||Issue Date:||2019||Source:||Brown, A. A. M., Hooper, T. J. N., Veldhuis, S. A., Chin, X. Y., Bruno, A., Vashishtha, P., . . . Mathews, N. (2019). Self-assembly of a robust hydrogen-bonded octylphosphonate network on cesium lead bromide perovskite nanocrystals for light-emitting diodes. Nanoscale, 11(25), 12370-12380. doi:10.1039/C9NR02566A||Journal:||Nanoscale||Abstract:||We report the self-assembly of an extensive inter-ligand hydrogen-bonding network of octylphosphonates on the surface of cesium lead bromide nanocrystals (CsPbBr3 NCs). The post-synthetic addition of octylphosphonic acid to oleic acid/oleylamine-capped CsPbBr3 NCs promoted the attachment of octylphosphonate to the NC surface, while the remaining oleylammonium ligands maintained the high dispersability of the NCs in non-polar solvent. Through powerful 2D solid-state 31P–1H NMR, we demonstrated that an ethyl acetate/acetonitrile purification regime was crucial for initiating the self-assembly of extensive octylphosphonate chains. Octylphosphonate ligands were found to preferentially bind in a monodentate mode through P–O−, leaving polar P[double bond, length as m-dash]O and P–OH groups free to form inter-ligand hydrogen bonds. The octylphosphonate ligand network strongly passivated the nanocrystal surface, yielding a fully-purified CsPbBr3 NC ink with PLQY of 62%, over 3 times higher than untreated NCs. We translated this to LED devices, achieving maximum external quantum efficiency and luminance of 7.74% and 1022 cd m−2 with OPA treatment, as opposed to 3.59% and 229 cd m−2 for untreated CsPbBr3 NCs. This represents one of the highest efficiency LEDs obtained for all-inorganic CsPbBr3 NCs, accomplished through simple, effective passivation and purification processes. The robust binding of octylphosphonates to the perovskite lattice, and specifically their ability to interlink through hydrogen bonding, offers a promising passivation approach which could potentially be beneficial across a breadth of halide perovskite optoelectronic applications.||URI:||https://hdl.handle.net/10356/138189||ISSN:||2040-3364||DOI:||10.1039/C9NR02566A||Rights:||© 2019 The Royal Society of Chemistry. All rights reserved. This paper was published in Nanoscale and is made available with permission of The Royal Society of Chemistry.||Fulltext Permission:||open||Fulltext Availability:||With Fulltext|
|Appears in Collections:||MSE Journal Articles|
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