Photoluminescence decay dynamics and mechanism of energy transfer in undoped and Mn ²⁺ doped ZnSe nanoparticles

Energy transfer dynamics in Mn ²⁺-doped ZnSe nanoparticles have been studied by monitoring the photoluminescence using time-integrated and time-resolved spectroscopic techniques. Upon Mn ²⁺ doping, static photoluminescence (PL) spectra show that the bandedge excitonic state is quenched and the characteristic Mn ²⁺ emission appears at 584 nm. Picosecond PL kinetics and femtosecond transient absorption studies have both found that the Mn ²⁺ doping substantially shortens the average lifetimes of the bandedge excitonic state as well as shallow trap states. The energy transfer from ZnSe to Mn ²⁺ likely follows two mechanisms, one mediated through trap states and another without.