Jump to main content
Jump to site search

Issue 45, 2016
Previous Article Next Article

Hot exciton cooling and multiple exciton generation in PbSe quantum dots

Author affiliations

Abstract

Multiple exciton generation (MEG) is a promising process to improve the power conversion efficiency of solar cells. PbSe quantum dots (QDs) have shown reasonably high MEG quantum yield (QY), although the photon energy threshold for this process is still under debate. One of the reasons for this inconsistency is the complicated competition of MEG and hot exciton cooling, especially at higher excited states. Here, we investigate MEG QY and the origin of the photon energy threshold for MEG in PbSe QDs of three different sizes by studying the transient absorption (TA) spectra, both at the band gap (near infrared, NIR) and far from the band gap energy (visible range). The comparison of visible TA spectra and dynamics for different pump wavelengths, below, around and above the MEG threshold, provides evidence of the role of the Σ transition in slowing down the exciton cooling process that can help MEG to take over the phonon relaxation process. The universality of this behavior is confirmed by studying QDs of three different sizes. Moreover, our results suggest that MEG QY can be determined by pump–probe experiments probed above the band gap.

Graphical abstract: Hot exciton cooling and multiple exciton generation in PbSe quantum dots

Back to tab navigation
Please wait while Download options loads

Supplementary files

Publication details

The article was received on 01 Jun 2016, accepted on 19 Oct 2016 and first published on 19 Oct 2016


Article type: Paper
DOI: 10.1039/C6CP03790A
Citation: Phys. Chem. Chem. Phys., 2016,18, 31107-31114
  •   Request permissions

    Hot exciton cooling and multiple exciton generation in PbSe quantum dots

    M. Kumar, S. Vezzoli, Z. Wang, V. Chaudhary, R. V. Ramanujan, G. G. Gurzadyan, A. Bruno and C. Soci, Phys. Chem. Chem. Phys., 2016, 18, 31107
    DOI: 10.1039/C6CP03790A

Search articles by author