Exciton recombination dynamics in zinc selenide quantum dots

The time dependent photoluminescence measurements of three different sized zinc selenide quantum dots are carried out. The existence of biexponential decay is explained with the help of three level model [ground state, singlet (bright exciton) state, and triplet (dark exciton) state]. The exciton recombination time of ZnSe quantum dots decreases with the reduction in quantum dot size. The decrease in exciton recombination time is attributed to enhanced overlap integral of electron and hole wavefunctions. This also indicates the dominance of the radiative recombination over the nonradiative recombination process.