Efficient and Stable Multicolor Emissions of the Coumarin‐Modified Cs₃LnCl₆ Lead‐Free Perovskite Nanocrystals and LED Application

Abstract

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 Cs3LnCl6 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 Cs3EuCl6 NCs as an intermediate state, Cs3EuCl6 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 Cs3EuCl6 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