Improved brightness and efficiency in Ce codoped ZnS:TbOF electroluminescent thin films

ZnS:TbOF alternating current thin film electroluminescent devices codoped with Ce by rf magnetron sputtering were shown to be brighter than Tb singly doped films. This brightness improvement is shown to results predominantly from increased radiative efficiency, with a secondary improvement in excitation efficiency. At 20 V above threshold for electroluminescence, V20, the radiative efficiency of Ce codoped films is improved ≈130%. The nonlinear exponential decay and improved efficiency of electroluminescent emission for Ce codoped films is attributed to energy transfer from Ce+3 to Tb+3 luminescent centers. The improved excitation efficiency is attributed to reduced space charge.