Carrier multiplication and cooling in semiconductor quantum dots

In semiconductor quantum dots (QDs), charge carrier cooling is in direct competition with carrier multiplication (CM), a process in which one absorbed photon excites two or more electrons that may improve the light conversion efficiency of photovoltaic devices. CM by an initially hot charge carrier occurs in competition with cooling, with the...

Asymmetric Optical Transitions Determine the Onset of Carrier Multiplication in Lead Chalcogenide Quantum Confined and Bulk Crystals

Carrier multiplication is a process in which one absorbed photon excites two or more electrons. This is of great promise to increase the efficiency of photovoltaic devices. Until now, the factors that determine the onset energy of carrier multiplication have not been convincingly explained. We show experimentally that the onset of carrier...

Broadband Cooling Spectra of Hot Electrons and Holes in PbSe Quantum Dots

Understanding cooling of hot charge carriers in semiconductor quantum dots (QDs) is of fundamental interest and useful to enhance the performance of QDs in photovoltaics. We study electron and hole cooling dynamics in PbSe QDs up to high energies where carrier multiplication occurs. We characterize distinct cooling steps of hot electrons and...