Enhanced Multiple Exciton Generation in PbS|CdS Janus-like Heterostructured Nanocrystals

Daniel M. Kroupa, Gregory F. Pach, Márton Vörös, Federico Giberti, Boris D. Chernomordik, Ryan W. Crisp, Arthur J. Nozik, Justin C. Johnson, Rohan Singh, Victor I Klimov, Giulia Galli, Matthew C. Beard

Research output: Contribution to journalArticle

12 Citations (Scopus)

Abstract

Generating multiple excitons by a single high-energy photon is a promising third-generation solar energy conversion strategy. We demonstrate that multiple exciton generation (MEG) in PbS|CdS Janus-like heteronanostructures is enhanced over that of single-component and core/shell nanocrystal architectures, with an onset close to two times the PbS band gap. We attribute the enhanced MEG to the asymmetric nature of the heteronanostructure that results in an increase in the effective Coulomb interaction that drives MEG and a reduction of the competing hot exciton cooling rate. Slowed cooling occurs through effective trapping of hot-holes by a manifold of valence band interfacial states having both PbS and CdS character, as evidenced by photoluminescence studies and ab initio calculations. Using transient photocurrent spectroscopy, we find that the MEG characteristics of the individual nanostructures are maintained in conductive arrays and demonstrate that these quasi-spherical PbS|CdS nanocrystals can be incorporated as the main absorber layer in functional solid-state solar cell architectures. Finally, based upon our analysis, we provide design rules for the next generation of engineered nanocrystals to further improve the MEG characteristics.

Original languageEnglish
JournalACS Nano
DOIs
Publication statusAccepted/In press - Jan 1 2018

    Fingerprint

Keywords

  • carrier multiplication
  • multiple excition generation
  • nanocrystal
  • quantum dot
  • solar cell
  • transient absorption spectroscopy

ASJC Scopus subject areas

  • Materials Science(all)
  • Engineering(all)
  • Physics and Astronomy(all)

Cite this

Kroupa, D. M., Pach, G. F., Vörös, M., Giberti, F., Chernomordik, B. D., Crisp, R. W., Nozik, A. J., Johnson, J. C., Singh, R., Klimov, V. I., Galli, G., & Beard, M. C. (Accepted/In press). Enhanced Multiple Exciton Generation in PbS|CdS Janus-like Heterostructured Nanocrystals. ACS Nano. https://doi.org/10.1021/acsnano.8b04850