Stable yellow light emission from lead-free copper halides single crystals for visible light communication

Abstract

Yellow light-emitting diodes (LEDs) as soft light have attracted abundant attention in lithography room, museum and art gallery. However, the development of efficient yellow LEDs lags behind green and blue LEDs, and the available perovskites yellow LEDs suffer from the instability. Herein, a pressure-assisted cooling method is proposed to grow lead-free CsCu 2 I 3 single crystals, which possess uniform surface morphology and enhanced photoluminescence quantum yield (PLQY) stability, with only 10% PLQY losses after being stored in air after 5000 ​h. Then, the single crystals used for yellow LEDs without encapsulation exhibit a decent Correlated Color Temperature (CCT) of 4290 ​K, a Commission Internationale de l'Eclairage (CIE) coordinate of (0.38, 0.41), and an excellent 570-h operating stability under heating temperature of 100 ​°C. Finally, the yellow LEDs facilitate the application in wireless visible light communication (VLC), which show a −3 dB bandwidth of 21.5 ​MHz and a high achievable data rate of 219.2 Mbps by using orthogonal frequency division multiplexing (OFDM) modulation with adaptive bit loading. The present work not only promotes the development of lead-free single crystals, but also inspires the potential of CsCu 2 I 3 in the field of yellow illumination and wireless VLC. The facile pressure-assisted cooling method is proposed to prepare lead-free CsCu2I3 single crystals, which promotes potential applications in both lighting for special occasions and wireless visible light communication.