The cooling dynamics of hot charge carriers in colloidal lead chalcogenide nanocrystals is studied by white light transient absorption spectroscopy. We demonstrate a transient accumulation of charge carriers at a high-energy critical point in the Brillouin zone. Using a theoretical study of the cooling rate in lead chalcogenides, we attribute this slowing down of charge carrier cooling to a phonon scattering bottleneck around this critical point. Our approach allows for the first ever determination of hot carrier cooling rates, relevant in e.g. modeling of multiple exciton generation.

A photoexcitation energy transfer process in blends of PbS QDs of different size is considered. An analysis of photoluminescence kinetics shows drastic increase of acceptor decay times. In a triple blend a merger of photoluminescence decay curves recorded at different spectral regions is found. Different pathways of the energy transfer, including the transfer from the in-gap state, are considered.

We report on the formation of photoactive hybrid structures based on multilayer graphene nanobelts and CdSe/ZnS quantum dots (QDs) on Pt microelectrodes. We have found that heat treatment in mild conditions enhances rate of electrical photoresponse of the hybrid structures due to elimination of long-lived charge traps. We also show that the electrical photoresponse polarity depends on the energy level structure of the QDs.

The interest in adopting hydrogen peroxide (H2O2) rocket propulsion systems has rekindled because H2O2 is more environmentally friendly than alternative propellants, has a high density to maximize the oxidizer-to-fuel ratio, and is able to be stored non-cryogenically. Simulations utilizing ab initio molecular dynamics have been generated to analyze the decomposition of H2O2 on the surface of a silver (Ag) metal cluster. The electronic structure for an atomic model of gaseous H2O2 molecules in the vicinity of an Ag13 cluster – one central Ag atom coordinated by the remaining twelve Ag atoms – was analyzed through density functional theory (DFT). After undergoing thermalization, the system was equilibrated at a high temperature of approximately 2000 K. The molecular dynamics did confirm that the Ag catalyst functions in facilitating the H2O2 decomposition to the final products of water and oxygen, while that the overall mechanism contains several intermediates.