Optical Property of Self-Doped PbSe Colloidal Quantum Dots

Observing the steady-state intraband transition of colloidal quantum dots has been a great challenge. For the last few years, there has been a rapid progress in realizing the steady-state intraband transition in colloidal quantum dots. The steady-state intraband transitions of self-doped Ag₂Se, HgSe, and β-HgS quantum dots have been successfully observed by varying the stoichiometry and surface dipole of the nanocrystal. Here, we present the interesting optical property of the PbSe quantum dots which appears near 10 μm without post-synthesis. We investigated the origin of the mid-IR absorption feature using FT-IR, X-ray photoelectron spectroscopy, and spectroelectrochemistry.