Photoluminescence decay dynamics and mechanism of energy transfer in undoped and Mn2+ doped ZnSe nanoparticles

Energy transfer dynamics in Mn2+-doped ZnSe nanoparticles have been studied by monitoring the photoluminescence using time-integrated and time-resolved spectroscopic techniques. Upon Mn2+ doping, static photoluminescence (PL) spectra show that the bandedge excitonic state is quenched and the characteristic Mn2+ emission appears at 584 nm. Picosecond PL kinetics and femtosecond transient absorption studies have both found that the Mn2+ doping substantially shortens the average lifetimes of the bandedge excitonic state as well as shallow trap states. The energy transfer from ZnSe to Mn2+ likely follows two mechanisms, one mediated through trap states and another without.