Small-Sized PbSe/PbS Core/Shell Colloidal Quantum Dots

Abstract

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