Quantum yield and luminous efficacy of thin-film ZnS electroluminescent emitters

The instantaneous values of the internal quantum yield and luminous efficacy of thin-film electroluminescent emitters are experimentally studied as functions of time, the mean field in the phosphor layer, and the charge passing through this layer. Also, the dependences of the internal quantum yield and luminous efficacy on the exciting voltage amplitude are explored. At exciting voltage frequencies above 10 Hz, the time dependences of the instantaneous quantum yield and luminous efficacy exhibit a dip in the range where the brightness and current through the phosphor layer grow and a peak in the range where the brightness and current decline. The dip and peak are related to the different rates of rise and fall of the brightness and current. (C) 2003 MAIK "Nauka/Interperiodica".