Non-rare earth containing BCNO phosphors: Chemical activation for LED application

To enhance luminescence performance is important, but still remains challenging owing to the constraints of traditional methods in tuning colors and utilizing the expansive rare earth elements. In this work, BCNO phosphors, without any rare earth elements, are synthesized using KOH as an activator for the first time to show tunable lights. Moreover, BCNO phosphors are successfully fabricated into LED lamps to exhibit blue to green light. Further investigations about the activating process of BCNO phosphors demonstrate that the presence of KOH not only prohibits the oxidation of C₃N₄ at lower temperature, but also activates the carbon and oxygen species involved in the final BCNO. Based on the data analyses about phase structures, chemical bonds, and electronic levels, the variations of the bonding levels related to carbon and oxygen as well as nitrogen defect levels are established. Accordingly, KOH content dependent emission intensity and red shift of emission peak are rationalized in terms of an increased transition probability of oxygen related levels and moved carbon related levels near to the conduction band. Activation mechanism of KOH for BCNO phosphors reported here may shed light on developing advanced luminescence materials.