ZnO-blended YOS phosphor is well-known to be excitable by low energy electrons.It has been found that the phosphor exhibiting a lower excitation threshold voltage and a higher brightness can be performed with ZnO by means of precipitation method as compared with the mechanical mixing method commonly used.The presence of ZnO has a double effects on the luminescence of YOS phosphor in device. Under lower anode voltage

ZnO always play an important role on maintaining the low energy electron excitation

whereas it will inhibit the emission of YOS as the anode voltage raises. Hence

there is an optimum ZnO-containing amount

which is perfectly dependent on the anode voltage applied.