Small-Sized PbSe/PbS Core/Shell\nColloidal Quantum\nDots

Abstract

The work focuses on the synthesis of small-sized PbSe/PbS\ncore/shell\ncolloidal quantum dots with the core diameter of 2–2.5 nm and\nthe shell thickness of 0.5–1.0 nm. The PbSe/PbS core/shell\nCQDs are chemically stable under time-limited air exposure and have\nemission quantum efficiency of 60% at room temperature. The PbSe/PbS\ncore/shell CQDs have a tunable absorption edge around 1 μm,\nlarge exciton emission Stokes shift (∼150 meV), and small exchange\ninteraction (∼1.5 meV). Theoretical calculations associate\nthe mentioned parameters to the small-size regime as well as to a\nlift of band-edge degeneracy due to slight shape anisotropy. The specific\nparameters are of special interest in photovoltaic applications.