Efficient And Stable Multi-Color Emissions of The Coumarin Modified Cs 3 LnCl 6 Lead-Free Perovskite Nanocrystals And Led Application.

Lanthanide-based lead-free perovskite materials hold great promise for the development of high-resolution full-color displays in the future. In this work, we systemically prepared various Cs 3 LnCl 6 perovskite nanocrystals (NCs) emitting light across the visible to near-infrared spectrum with remarkably high photoluminescence quantum yield (PLQY). Especially, by introducing multifunctional coumarin small molecules into Cs 3 EuCl 6 NCs as an intermediate state, Cs 3 EuCl 6 NCs can achieve an impressive PLQY of 92.4% with pure red emission and an exceptional ET efficiency of nearly 93.2%. Furthermore, we successfully fabricated the lanthanide-based electroluminescent devices in red, green, and blue. Among them, the Cs 3 EuCl 6 NCs based red LED demonstrates a full width at half maximum (FWHM) of 18 nm at 617 nm, an external quantum efficiency (EQE) up to 5.17% and a maximum brightness of 2373 cd m -2 , which is the most excellent reported for lead-free narrowband (within 20 nm) emission devices. Notably, these devices exhibit an operating half-life of 440 hours at a brightness level of 100 cd m -2 , surpassing the performance of most reported lead-free perovskite LEDs (PLEDs). Our work opens up exciting possibilities for the future commercialization of lanthanide-based PLEDs in the display industry, paving the way for more vibrant, energy-efficient, and long-lasting display technologies. This article is protected by copyright. All rights reserved.