Mn-doped nanocrystals in light-emitting diodes: energy-transfer to obtain electroluminescence from quantum dots

Abstract

We fabricate light-emitting diodes (LEDs) based on Mn-doped ZnS nanocrystals along with hole-transporting N,N' bis(3-methylphenyl)-N,N'-diphenyl-benzidine (TPD). With Mn-doping, ZnS nanostructures exhibit a strong photoluminescence. The LEDs exhibit electroluminescence (EL) from Mn-doped ZnS quantum dots and TPD. In order to open up channels for energy-transfer from TPD to quantum dots and to achieve EL from only the nanoparticles, we grow core-shell nanoparticles with Mn-doped ZnS in the core and CdS as the shell layer. Excitons formed in TPD can now transfer their energy directly to the shell-layer to yield EL from only the nanoparticles.