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

ABSTRACT: 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 holes and build up a broadband cooling spectrum for both charge carriers. Cooling of electrons is slower than of holes. At energies near the band gap we find cooling times between successive electronic energy levels in the order of 0.5 ps. We argue that here the large spacing between successive electronic energy levels requires cooling to occur by energy transfer to vibrational modes of ligand molecules or phonon modes associated with the QD surface. A

SUBMITTER: Spoor FCM 

PROVIDER: S-EPMC5492216 | biostudies-literature | 2017 Jun

REPOSITORIES: biostudies-literature