Performance enhanced light-emitting diodes fabricated from nanocrystalline CsPbBr3 with in situ Zn2+ addition

• Main Authors: 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, Hanna, John V.
• Other Authors: School of Materials Science and Engineering
• Format: Article
• Language: English
• Published: 2020
• Subjects: Engineering::Materials; All-inorganic Perovskite Nanocrystals; Light-emitting Diodes
• Online Access: https://hdl.handle.net/10356/145119
• Institution: Nanyang Technological University

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%.