Ligand-assisted solid phase synthesis of mixed-halide perovskite nanocrystals for color-pure and efficient electroluminescence

Simon F Solari; Sudhir Kumar; Jakub Jagielski; Nikolas M Kubo; Frank Krumeich; Chih-Jen Shih

doi:10.1039/d0tc04667a

Ligand-assisted solid phase synthesis of mixed-halide perovskite nanocrystals for color-pure and efficient electroluminescence

J Mater Chem C Mater. 2021 Mar 25;9(17):5771-5778. doi: 10.1039/d0tc04667a.

Authors

Simon F Solari¹, Sudhir Kumar¹, Jakub Jagielski¹, Nikolas M Kubo¹, Frank Krumeich², Chih-Jen Shih¹

Affiliations

¹ Institute for Chemical and Bioengineering, Department of Chemistry and Applied Biosciences, ETH Zürich Vladimir Prelog Weg 1 CH-8093 Zürich Switzerland chih-jen.shih@chem.ethz.ch.
² Laboratory of Inorganic Chemistry, Department of Chemistry and Applied Biosciences, ETH Zürich Vladimir Prelog Weg 1 CH-8093 Zürich Switzerland.

Abstract

Colloidal nanocrystals (NCs) of lead halide perovskites have generated considerable interest in the fabrication of optoelectronic devices, such as light emitting-diodes (LEDs), because of their tunable optical bandgap, narrow spectral width, and high defect tolerance. However, the inhomogeneous halide distribution within individual NCs remains a critical challenge in order to obtain color-stable electroluminescence in mixed-halide systems. Here, we demonstrate a new post-synthetic approach, ligand-assisted solid phase synthesis (LASPS), for the preparation of electroluminescent colloidal NCs of methylammonium (MA) lead halide perovskites, at room temperature. The slow reaction kinetics preserves the morphology, size, and shape in the resulting NCs whose emission covers the entire visible spectral region with photoluminescence (PL) quantum yields (QYs) of up to >90% and colloidal stability up to several months. The LEDs fabricated using the prepared mixed-halide NCs display narrowband electroluminescence (EL) ranging from 476 to 720 nm. The optimized red LEDs exhibit an external quantum efficiency, η _ext, of up to 2.65%, with the CIE 1931 color coordinates of (0.705, 0.290), nearly identical to those of the red primary in the recommendation (rec.) 2020 standard (0.708, 0.292).