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

Journal article (2018)

Authors

F.C.M. Spoor ChemE/Opto-electronic Materials - AS , Science Education and Communication - AS
G. Grimaldi ChemE/Opto-electronic Materials - AS
Christophe Delerue IEMN Institut d'Electronique de Microelectronique et de Nanotechnologie
W.H. Evers BN/Technici en Analisten
R.W. Crisp ChemE/Opto-electronic Materials - AS
P.A. Geiregat Universiteit Gent, ChemE/Opto-electronic Materials - AS
Zeger Hens Universiteit Gent
A.J. Houtepen ChemE/Opto-electronic Materials - AS
L.D.A. Siebbeles ChemE/Opto-electronic Materials - AS
Research Group
ChemE/Opto-electronic Materials (AS) (TU Delft)
Copyright: © 2018 F.C.M. Spoor, G. Grimaldi, Christophe Delerue, W.H. Evers, R.W. Crisp, P.A. Geiregat, Zeger Hens, A.J. Houtepen, L.D.A. Siebbeles
DOI: https://doi.org/10.1021/acsnano.8b01530
More Info
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Published Date

2018

Language

English

Faculty

Applied Sciences

Department

ChemE/Chemical Engineering

Research Group

ChemE/Opto-electronic Materials

Abstract

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 multiplication in lead chalcogenide quantum confined and bulk crystals is due to asymmetric optical transitions. In such transitions most of the photon energy in excess of the band gap is given to either the hole or the electron. The results are confirmed and explained by theoretical tight-binding calculations of the competition between impact ionization and carrier cooling. These results are a large step forward in understanding carrier multiplication and allow for a screening of materials with an onset of carrier multiplication close to twice the band gap energy. Such materials are of great interest for development of highly efficient photovoltaic devices.