Organic light-emitting diodes (OLEDs) are becoming the primary display technology in smartphones, smartwatches and televisions as they exhibit excellent contrast, colour reproduction and low power consumption. Central to the performance of commercialized green and red OLEDs is the organometallic phosphorescent emitter, which is responsible for the conversion of electrical energy into light with near unity internal quantum efficiency (IQE), as these complexes show simultaneously high photoluminescence quantum yields (FPL) and can efficiently harvest both singlet and triplet excitons to produce light in the device. However, the blue sub pixel in OLEDs presently uses an organic fluorophore as there do not exist phosphorescent OLEDs that are sufficiently stable or bright for commercial use, and few reported examples of phosphorescent emitters that are close to the BT.2020 industry standard for blue, defined as CIE coordinates of (0.131, 0.046). 9