CsPbBr/CsPbBr perovskite composites for WLEDs: pure white, high luminous efficiency and tunable color temperature.

CsPbBr/CsPbBr perovskite composites are fabricated by room-temperature one-pot mixing synthesis, which is short in time, free from inert gases and delivers a high product yield. Temperature-dependent photoluminescence shows that a larger exciton binding energy of 291.1 meV exhibits better thermal stability compared with that of pure CsPbBr and CsPbBr materials. The CIE chromaticity coordinates (0.1380, 0.7236) of green LEDs designed with CsPbBr/CsPbBr perovskite composites show almost no variation under driving current changing from 5 to 30 mA. Furthermore, the ground CsPbBr/CsPbBr perovskite composites mixed with red emitting KSiF:Mn phosphor are dropped and casted on a blue-emitting InGaN chip. The white light emitting diodes (WLEDs) are presented, which have good luminous efficiency of 65.33 lm W at 20 mA, a correlated color temperature of 5190 K, and the white gamut with chromaticity coordinate of (0.3392, 0.3336). According to the state of art, these excellent characteristics observed are much superior to the reported results of conventional perovskite-based WLEDs, which demonstrate the immense potential and great prospect of CsPbBr/CsPbBr perovskite composites to replace conventional phosphors in lighting devices.