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

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 hetero-nanostructures 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 hetero-nanostructure 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 by 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.

Authors:
 [1];  [2]; ORCiD logo [3]; ORCiD logo [4];  [2];  [1]; ORCiD logo [1]; ORCiD logo [2];  [5]; ORCiD logo [5];  [3]; ORCiD logo [2]
  1. National Renewable Energy Lab. (NREL), Golden, CO (United States); Univ. of Colorado, Boulder, CO (United States)
  2. National Renewable Energy Lab. (NREL), Golden, CO (United States)
  3. Univ. of Chicago, IL (United States); Argonne National Lab. (ANL), Argonne, IL (United States)
  4. Univ. of Chicago, IL (United States)
  5. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Publication Date:
Research Org.:
Energy Frontier Research Centers (EFRC) (United States). Center for Advanced Solar Photophysics (CASP); National Renewable Energy Lab. (NREL), Golden, CO (United States); Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
1471985
Alternate Identifier(s):
OSTI ID: 1489380
Report Number(s):
NREL/JA-5900-71834
Journal ID: ISSN 1936-0851
Grant/Contract Number:  
AC36-08GO28308; AC02-06CH11357
Resource Type:
Accepted Manuscript
Journal Name:
ACS Nano
Additional Journal Information:
Journal Volume: 12; Journal Issue: 10; Journal ID: ISSN 1936-0851
Publisher:
American Chemical Society (ACS)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; 77 NANOSCIENCE AND NANOTECHNOLOGY; quantum dots; multiple exciton generation; solar energy conversion; nanocrystal; solar cell; carrier multiplication; multiple excition generation; quantum dot; transient absorption spectroscopy

Citation Formats

Kroupa, Daniel M., Pach, Gregory F., Vörös, Márton, Giberti, Federico, Chernomordik, Boris D., Crisp, Ryan W., Nozik, Arthur J., Johnson, Justin C., Singh, Rohan, Klimov, Victor I., Galli, Giulia, and Beard, Matthew C. Enhanced Multiple Exciton Generation in PbS|CdS Janus-like Heterostructured Nanocrystals. United States: N. p., 2018. Web. doi:10.1021/acsnano.8b04850.
Kroupa, Daniel M., Pach, Gregory F., Vörös, Márton, Giberti, Federico, Chernomordik, Boris D., Crisp, Ryan W., Nozik, Arthur J., Johnson, Justin C., Singh, Rohan, Klimov, Victor I., Galli, Giulia, & Beard, Matthew C. Enhanced Multiple Exciton Generation in PbS|CdS Janus-like Heterostructured Nanocrystals. United States. doi:10.1021/acsnano.8b04850.
Kroupa, Daniel M., Pach, Gregory F., Vörös, Márton, Giberti, Federico, Chernomordik, Boris D., Crisp, Ryan W., Nozik, Arthur J., Johnson, Justin C., Singh, Rohan, Klimov, Victor I., Galli, Giulia, and Beard, Matthew C. Fri . "Enhanced Multiple Exciton Generation in PbS|CdS Janus-like Heterostructured Nanocrystals". United States. doi:10.1021/acsnano.8b04850. https://www.osti.gov/servlets/purl/1471985.
@article{osti_1471985,
title = {Enhanced Multiple Exciton Generation in PbS|CdS Janus-like Heterostructured Nanocrystals},
author = {Kroupa, Daniel M. and Pach, Gregory F. and Vörös, Márton and Giberti, Federico and Chernomordik, Boris D. and Crisp, Ryan W. and Nozik, Arthur J. and Johnson, Justin C. and Singh, Rohan and Klimov, Victor I. and Galli, Giulia and Beard, Matthew C.},
abstractNote = {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 hetero-nanostructures 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 hetero-nanostructure 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 by 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.},
doi = {10.1021/acsnano.8b04850},
journal = {ACS Nano},
number = 10,
volume = 12,
place = {United States},
year = {2018},
month = {9}
}

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