Optical Properties of PbS/CdS Core/Shell Quantum Dots

Abstract

We determine the optical properties of PbS/CdS core/shell QDs, addressing the energy and the oscillator strength of the first exciton transition and the intrinsic absorption coefficient at short wavelengths. It follows that the intrinsic absorption coefficient at wavelengths of 350 and 400 nm agrees with theoretical numbers predicted using the Maxwell-Garnett model. Moreover, close correspondence is demonstrated between the energy and the oscillator strength of the first exciton transition of PbS/CdS core/shell and PbS QDs with a similar core size. This provides a straightforward, way to estimate the PbS core diameter in PbS/CdS core/shell quantum dots by means of the PbS sizing curve, and it indicates that PbS/CdS QDs exhibit a type 1 band alignment.