Efficient steplike carrier multiplication in percolative networks of epitaxially connected PbSe nanocrystals

Kulkarni, A; Evers, WH; Tomic, S; Beard, MC; Vanmaekelbergh, D; Siebbeles, LDA

Abstract

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.

Citation

Kulkarni, A., Evers, W., Tomic, S., Beard, M., Vanmaekelbergh, D., & Siebbeles, L. (2017). Efficient steplike carrier multiplication in percolative networks of epitaxially connected PbSe nanocrystals. ACS nano, 12(1), 378-384. https://doi.org/10.1021/acsnano.7b06511

• Journal Article Type: Article
• Acceptance Date: Dec 14, 2017
• Online Publication Date: Dec 14, 2017
• Publication Date: Dec 14, 2017
• Deposit Date: Jan 3, 2018
• Publicly Available Date: Jan 3, 2018
• Journal: ACS Nano
• Print ISSN: 1936-0851
• Publisher: American Chemical Society
• Volume: 12
• Issue: 1
• Pages: 378-384
• DOI: https://doi.org/10.1021/acsnano.7b06511
• Keywords: carrier multiplication, charge carrier mobility, nanocrystal networks, solar cell efficiency, terahertz spectroscopy
• Publisher URL: http://dx.doi.org/10.1021/acsnano.7b06511
• Related Public URLs: http://pubs.acs.org/journal/ancac3
• Additional Information: Funders : Foundation for Fundamental Research on Matter (FOM)