Zero-dimensional cadmium halide with broad band yellow light emission for white light-emitting diodes†

Abstract

Recently, low-dimensional organic–inorganic metal halide perovskites acting as white-light-emitting materials have been widely studied in the field of optoelectronics and solid-state lighting owing to their facile preparation and excellent optical characteristics. However, the luminescence efficiency and light stability of white-light-emitting diodes (WLEDs) are hindered by the re-absorption of mixing phosphors due to the difference in light decay. Herein, we report for the first time a new zero-dimensional (0D) cadmium halide of (BAPPz)Cd₂Br₈·2H₂O with [CdX₄]²⁻ as an optically active center, which emits broadband yellow light with a PLQY of 13.78%. Significantly, (BAPPz)Cd₂Br₈·2H₂O could be used as a new phosphor for a white-light-emitting diode doped with a trace of blue commercial phosphor, which achieved a high color rendering index (CRI) of 93.7 and had a correlated color temperature (CCT) close to the domestic standard light source D65 (6500 K). With the driving current of the WLED device increasing from 20 mA to 120 mA, CRI values were consistently high (>90). This work not only demonstrates a new orientation to fabricate light-emitting diodes with high CRI values but also highlights its potential application in the development of energy-efficient white-light-emitting diodes.