Optical Properties of PbS/CdS Core/Shell Quantum Dots

Abstract

We\ndetermine the optical properties of PbS/CdS core/shell QDs,\naddressing the energy and the oscillator strength of the first exciton\ntransition and the intrinsic absorption coefficient at short wavelengths.\nIt follows that the intrinsic absorption coefficient at wavelengths\nof 350 and 400 nm agrees with theoretical numbers predicted using\nthe Maxwell–Garnett model. Moreover, close correspondence is\ndemonstrated between the energy and the oscillator strength of the\nfirst exciton transition of PbS/CdS core/shell and PbS QDs with a\nsimilar core size. This provides a straightforward way to estimate\nthe PbS core diameter in PbS/CdS core/shell quantum dots by means\nof the PbS sizing curve, and it indicates that PbS/CdS QDs exhibit\na type 1 band alignment.