Efficiently Luminescent and Stable Lead‐free Cs3Cu2Cl5@Silica Nanocrystals for White Light‐Emitting Diodes and Communication

Abstract The poor stability of lead‐free Cs 3 Cu 2 Cl 5 nanocrystals (NCs) is the main impediment for their broad practical applications. Here, a sol‐gel reaction using tetraethoxysilane (TEOS) as the silica coating precursor to prepare Cs 3 Cu 2 Cl 5 @SiO x NCs is proposed. Due to the efficient passivation and robust protection of SiO x shells on the NCs surface, Cs 3 Cu 2 Cl 5 @SiO x NCs solution and films exhibit a high photoluminescence quantum yield of 98% and 76%, respectively, and improved stability against water and heat. Cs 3 Cu 2 Cl 5 @SiO x NCs are then used to fabricate warm white light‐emitting diodes (WLEDs), which show a high color‐rendering index of 94 and a proper correlated color temperature of 5049 K, and maintain an excellent thermal (265–360 K) and prolonged operating (380 h) stability. In addition, the good white light emission facilitates the application in visible light communication (VLC). The VLC light source demonstrates a −3 dB bandwidth of 420 kHz, and the achieved data rate of the VLC system reaches 2.65 Mbps using orthogonal frequency division multiplexing modulation with a bit loading. As a result, lead‐free Cs 3 Cu 2 Cl 5 @SiO x NCs with an efficient optical performance and an excellent stability might promote the development of stable NCs and extend the applications in optoelectronics.