A Mechanochemically Synthesized Hybrid Bismuth Halide as Highly Efficient Red Phosphor for Blue Chip-Based WLED

Abstract

In recent decades, white light-emitting diodes (WLEDs) assembled by blue light-emitting diodes (LEDs) and down-conversion phosphors have gained rapid development. Thereinto, red phosphors, especially for the ecofriendly and cost-effective ones, serve an important role for the preparation of superior WLEDs. Herein, a halide compound with a 0D crystal structure, namely [PPh4]2[Bi2Br8(bp4do)(DMSO)2] (BiBrON, PPh4 = tetraphenylphosphonium, bp4do = 4,4′-bipyridine 1,1′-dioxide, DMSO = dimethyl sulfoxide) is synthesized at gram scale via a mechanochemical synthesis method. Photophysical properties of BiBrON are investigated in detail. BiBrON has the highest efficiency (78.20%) of red phosphorescence among the Bi-based halides. The red emission of BiBrON is blue-light-excitable with 99.9% color purity and outstanding thermal stability below 400 K. The optical absorption-emission mechanism in BiBrON is elucidated by the combination study of experiments and density functional theory calculations. BiBrON can be applied as a red phosphor in the blue LED chip-based WLED with high color rendering index of 87.8, that is higher than the one fabricated utilizing commercial red phosphor (610 nm), and ideal Commission International de l'Eclairage chromaticity coordinate of (0.3282, 0.3311). This work demonstrates for the first time the great potential of Bi-inorganic–organic hybrid material as phosphors applied for WLED.