Manganese concentration dependent saturation in ZnS:Mn thin film electroluminescent devices

The decay rate of the yellow emission in ZnS:Mn thin film electroluminescent devices increases at high luminance levels and a larger increase is observed for higher manganese concentrations. A stronger saturation of the emission is also observed when the manganese concentration is high. The experimental results suggest nonradiative decay caused by an interaction between excited Mn2+ which occurs by energy transfer via unexcited Mn2+. An increase in the current density in the ZnS:Mn layer is observed simultaneously with the higher decay rate of the emission, which indicates that free electrons are created in the interaction between excited Mn2+.