Performance Enhanced Light-Emitting Diodes Fabricated from Nanocrystalline CsPbBr3 with In Situ Zn2+ Addition

Vashishtha, Parth, Griffith, Benjamin E., Brown, Alasdair A.m., Hooper, Thomas J.n., Fang, Yanan, Ansari, Mohammed S., Bruno, Annalisa, Pu, Suan Hui, Mhaisalkar, Subodh G., White, Tim and Hanna, John V. (2020) Performance Enhanced Light-Emitting Diodes Fabricated from Nanocrystalline CsPbBr3 with In Situ Zn2+ Addition. ACS Applied Electronic Materials, 2 (12), 4002-4011. (doi:10.1021/acsaelm.0c00827).

Abstract

Inorganic cesium lead halide perovskite nanocrystals are promising materials for optoelectronic applications as they exhibit high thermal stability alongside precise color tunability and high color purity; however, their optical properties are degraded by surface defects. This work demonstrates a room temperature synthesis of CsPbBr3 nanocrystals facilitating in situ surface passivation via the incorporation of Zn2+ cations. The facile incorporation ZnBr2 into the precursor solution facilitates Zn2+ and Br− substitution into the nanocrystal surface/subsurface layers to induce passivation of existing Pb2+ and Br– vacancies and increase the photoluminescence quantum yield from ∼48 to 86%. The XPS and solid-state 1H MAS NMR techniques show that the key modification is a reduction of the octylamine:oleic acid ratio leading to a near-neutral surface charge; this is accompanied by the appearance of larger nanosheets and nanowires observed by quantitative powder XRD and HR-TEM. The suitability of these perovskite nanocrystals for electrically driven applications was confirmed by the fabrication of light-emitting diodes, which demonstrate that the in situ Zn2+ passivation strategy enhanced the external quantum efficiency by ∼60%.

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Contributors

Author: Alasdair A.m. Brown

Author: Suan Hui Pu

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