Efficient Steplike Carrier Multiplication in Percolative Networks of Epitaxially Connected PbSe Nanocrystals

Efficient Steplike Carrier Multiplication in Percolative Networks of Epitaxially Connected PbSe Nanocrystals

Kulkarni, A. (TU Delft ChemE/Opto-electronic Materials)
Evers, W.H. (TU Delft BN/Technici en Analisten)
Tomić, Stanko (University of Salford)
Beard, Matthew C. (National Renewable Energy Laboratory)
Vanmaekelbergh, Daniel (Debye Institute)
Siebbeles, L.D.A. (TU Delft ChemE/Opto-electronic Materials)

2018

Carrier multiplication (CM) is a process in which a single photon excites two or more electrons. CM is of interest to enhance the efficiency of a solar cell. Until now, CM in thin films and solar cells of semiconductor nanocrystals (NCs) has been found at photon energies well above the minimum required energy of twice the band gap. The high threshold of CM strongly limits the benefits for solar cell applications. We show that CM is more efficient in a percolative network of directly connected PbSe NCs. The CM threshold is at twice the band gap and increases in a steplike fashion with photon energy. A lower CM efficiency is found for a solid of weaker coupled NCs. This demonstrates that the coupling between NCs strongly affects the CM efficiency. According to device simulations, the measured CM efficiency would significantly enhance the power conversion efficiency of a solar cell.

carrier multiplication
charge carrier mobility
nanocrystal networks
solar cell efficiency
terahertz spectroscopy

http://resolver.tudelft.nl/uuid:46fb8df2-7066-492b-b560-deca45f033d1

https://doi.org/10.1021/acsnano.7b06511

1936-0851

ACS Nano (online), 12 (1), 378-384

Institutional Repository

journal article

© 2018 A. Kulkarni, W.H. Evers, Stanko Tomić, Matthew C. Beard, Daniel Vanmaekelbergh, L.D.A. Siebbeles