Color-stable highly luminescent sky-blue perovskite light-emitting diodes

Perovskite light-emitting diodes (PeLEDs) have shown excellent performance in the green and near-infrared spectral regions, with high color purity, efficiency, and brightness. In order to shift the emission wavelength to the blue, compositional engineering (anion mixing) and quantum-confinement engineering (reduced-dimensionality) have been employed. Unfortunately, LED emission profiles shift with increasing driving voltages due to either phase separation or the coexistence of multiple crystal domains. Here we report color-stable sky-blue PeLEDs achieved by enhancing the phase monodispersity of quasi-2D perovskite thin films. We selected cation combinations that modulate the crystallization and layer thickness distribution of the domains. The perovskite films show a record photoluminescence quantum yield of 88% at 477 nm. The corresponding PeLEDs exhibit stable sky-blue emission under high operation voltages. A maximum luminance of 2480 cd m-2 at 490 nm is achieved, fully one order of magnitude higher than the previous record for quasi-2D blue PeLEDs.Q.X. acknowledges financial support from Singapore National Research Foundation via the Investigatorship Award (NRF-NRFI2015-03) and the Competitive Research Programme (NRF-CRP14-2014-03), and Singapore Ministry of Education through AcRF Tier 2 and Tier 1 grants (MOE2015-T2-1-047 and RG 113/16). E.H.S. and all co-authors from the Department of Electrical and Computer Engineering at the University of Toronto acknowledge the financial support by the US Department of the Navy, Office of Naval Research (Grant Award No: N00014-17-1-2524), by the Ontario Research Fund—Research Excellence Program, and by the Natural Sciences and Engineering Research Council of Canada (NSERC). H.T. acknowledges the Netherlands Organisation for Scientific Research (NWO) for a Rubicon grant (680-50-1511) in support of his postdoctoral research at the University of Toronto. Computations were performed on the GPC supercomputer at the SciNet HPC Consortium. SciNet is funded by the Canada Foundation for Innovation under the auspices of Compute Canada; the Government of Ontario; Ontario Research Fund—Research Excellence; and the University of Toronto