Deciphering the emission dynamics of colloidal PbS quantum dots: a spectroscopic exploration under diverse environmental and experimental conditions.

This study employs a combination of spectroscopic techniques, including absorption, photoluminescence (PL), time-resolved PL kinetics, and transient absorption measurements, to elucidate the dynamics of excited states of oleic acid (OA)-capped colloidal PbS quantum dots (QDs) in toluene with a mean size of approximately 3 nm. PL decay profiles were properly treated employing either fitting or fitting-free models to extract average decay lifetimes and lifetime distributions. Our findings highlight the profound impact of factors such as particle concentration, size, surface treatment, and the surrounding environment on the optical properties of PbS QDs.

Two-step light conversion with quantum dots inside non-linear crystals.

Up-conversion of infrared (IR) to visible light is demonstrated via an unconventional two-step process combining second harmonic generation with photoluminescence. This is achieved in a composite material formed by single crystals of KHPO (KDP), in which CdTe/CdS quantum dots (QDs) are embedded during a crystal growth. The second harmonic generation from the IR laser frequency in KDP takes place, and then, generated light is absorbed by QDs and luminescence is emitted.