Novel emitting system based on a multifunctional bipolar phosphor : an effective approach for highly efficient warm-white light-emitting devices with high color-rendering index at high luminance.

A three-color warm-white organic light-emitting diode employing an efficient phosphor–phosphor type host–guest emitting system achieves efficiencies of 27.3% for external quantum efficiency and 74.5 lm W–1 for power efficiency at a luminance of 1000 cd m–2, which maintained the high levels of 24.3% and 45.8 lm W−1 at 10 000 cd m−2, with a stable color-rendering index of 86–87