The CIE coordinates of the TSPO1 devices with cD of 1.5 wt% are (0.173, 0.055), values that are very close to the Rec.2020 standard for primary blue in UHDTV (0.131, 0.046). Increasing the doping concentration of the emitter resulted in the expected reduced colour purity of the device, reflected in the CIE coordinates of (0.176, 0.068) and (0.187, 0.103), respectively, for the 3 wt% and 6 wt% devices.