The Effect of Exciton-Delocalizing Thiols on Intrinsic Dual Emitting Semiconductor Nanocrystals

The emissive properties of thiol‐capped CdSe nanocrystals (NCs) with intrinsic dual emission are investigated through temperature‐dependent photoluminescence (PL) measurements. We demonstrate the influence of thiols on the relative PL intensities of the core and surface emissive states, as well as on the observed Stokes shifts. A redshift of both the core and surface PL in comparison with phosphonate‐capped NCs is consistent with recent work exploring the effect of thiols as excitonic hole‐delocalizing ligands. This observation is consistent with prior reports suggesting that surface excitons originate from electrons bound to cadmium trap states. The ligand effect: The temperature‐dependent emissive properties of thiol‐capped dual emitting CdSe nanocrystals are studied. Based on relative differences in their steric bulk and electronic properties, three distinct thiols were chosen (see picture) and the influence of the thiols on the relative PL intensities of the core and surface emissive states and on the observed Stokes shifts were revealed.