Issue 19, 2021

Stable down-conversion white light-emitting devices based on highly luminescent copper halides synthesized at room temperature

Abstract

In recent years, the metal-halide perovskites have attracted intensive attention in the field of white light-emitting devices (WLEDs). However, their further commercial applications are severely hampered by the poor stability and lead toxicity of such materials. In this work, we demonstrate two types of lead-free ternary copper halides (blue-emissive Cs3Cu2I5 and yellow-emissive CsCu2I3), which were synthesized by a convenient supersaturated recrystallization method at room temperature. Both materials have particularly good crystallinity and excellent stability against ultraviolet light, heat, and air oxygen/moisture. Temperature-dependent photoluminescence (PL) and time-resolved PL decay measurements confirm that the highly luminescent and largely Stokes-shifted broadband emission of both materials derived from the self-trapped exciton-related recombination. By using a mixture of Cs3Cu2I5 and CsCu2I3 as the down-conversion phosphors, a high-performance WLED is demonstrated with the color coordinates of (0.324, 0.330), a correlated color temperature of 5877 K, and a color rendering index of 88.4. Also, a high luminous efficiency of 54.6 lm W−1 is realized, which is the highest value among the lead-free perovskite-based WLEDs. More importantly, the studied WLED demonstrates excellent operation stability, and almost no emission degradation occurs after continuously working for 100 h in air ambient. The results suggest that such ternary copper halides may be potentially attractive candidates for the fabrication of efficient, stable, and environmentally friendly WLEDs.

Graphical abstract: Stable down-conversion white light-emitting devices based on highly luminescent copper halides synthesized at room temperature

Supplementary files

Article information

Article type
Communication
Submitted
05 mar 2021
Accepted
09 apr 2021
First published
10 apr 2021

J. Mater. Chem. C, 2021,9, 6151-6159

Stable down-conversion white light-emitting devices based on highly luminescent copper halides synthesized at room temperature

L. Wang, Z. Ma, F. Zhang, M. Wang, X. Chen, D. Wu, Y. Tian, X. Li and Z. Shi, J. Mater. Chem. C, 2021, 9, 6151 DOI: 10.1039/D1TC01037A

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