Chlorinated yellow phosphorescent cyclometalated neutral iridophosphors featuring broad emission bandwidths for white electroluminescence

The efficient yellow phosphors with broad emission bandwidths play quite important roles in the realization of high-performance two-color white organic light-emitting devices (OLEDs). Herein, by using a chlorine-functionalization method, we designed three efficient yellow iridium(III) complexes (Ir1–Ir3) bearing chlorine atoms. At room temperature, these phosphors exhibit bright yellow phosphorescence with emission wavelengths of 549–574 nm and high photoluminescence efficiency of 0.49–0.73 in the N₂-saturated dichloromethane. Importantly, these complexes feature extremely broad emission bandwidths (reaching 104 nm), making them the record-high values in the yellow iridium(III) phosphors reported so far. Using these complexes as the triplet dopants, the prepared OLEDs show yellow phosphorescence with the emission maximum at 565, 548, and 551 nm, respectively. The extremely high external quantum efficiency of 23.8% was realized for the as-prepared yellow OLEDs. Furthermore, Ir2-based two-color white OLED with high spectral quality was also realized, and the color rendering index and CIE coordinates for two-color white OLED are 74 and (0.32, 0.34), respectively. The broad yellow emission band and high-efficiency of the device proved that these phosphors show great potentials in developing high-performance yellow and white electroluminescence.