Tuning Both Bandedge Exciton Dynamics and Energy Transfer Dynamics in Mn-Doped QDs via Doping of Ag Co-Dopants

Abstract

Doping in colloidal semiconductor nanocrystals (NCs) is an attractive approach for giving new functionalities which come from enhanced interactions between strongly quantum confined band-edge exciton wavefunction and dopant ions. However, fundamental analyses on doped NCs such as precise location and site(interstitial/substitutional) of dopants and correlations between co-dopants were rarely reported because of physical complexity of the system. Here we investigated role of Ag co- dopants in Mn-doped NCs through spectroscopic approaches. Through sophisticated and multi-step, cation exchange and shell overcoating processes, we successfully synthesized co-doped NCs with well-defined doping depth and dopant concentration. With different doping concentration of Ag ions, two completely different trends arise in intensity changes of both band-edge photoluminescence (PL) and Mn dopant sensitized phosphorescence. We also figured out that they are also affected by relative distribution between Mn and Ag ions which shows possibility of sensitive tuning of branching between band-edge dynamics and energy transfer dynamics.