Low-Temperature Solution Synthesis of Stable Cs₃Cu₂Br₅ Single Crystals for Visible Light Communications

Inorganicperovskites CsPbX3 (X = Cl, Br, I) have showngreat potential as luminescent materials for a wide range of photoelectricdevices. However, the practical use of these materials is limiteddue to the toxicity of lead and poor stability. Here, we present afacile low-temperature, solution-based method to synthesize lead-freeand highly stable Cs3Cu2Br5 singlecrystals (SCs) without the use of organic solvents. Owing to the self-trappedexciton emissions, Cs3Cu2Br5 SCsexhibit a strong broadband blue emission with a high photoluminescencequantum yield (PLQY) upon 254 nm ultraviolet light excitation. Inaddition, the Cs3Cu2Br5 SCs showa high stability against heat, humidity, and UV light. Therefore,the Cs3Cu2Br5 SCs are utilized asemitters in white light emitting diodes (WLEDs), demonstrating a highcolor rendering index of 81 and a decent commission internationalede l'Eclairage coordinate of (0.30, 0.34). Furthermore, theprepared WLEDs are used in wireless visible light communications,showing a -3 dB bandwidth of 6.7 MHz and an achievable datarate of 45 Mbps. Our study provides a novel organic-solvent-free,low-temperature method to synthesize Cs3Cu2Br5 SCs and could promote the development of Cu-based metal halidesin visible light communications.