Enhanced Multiple Exciton Generation in PbS|CdS Janus-like Heterostructured Nanocrystals
- National Renewable Energy Lab. (NREL), Golden, CO (United States); Univ. of Colorado, Boulder, CO (United States)
- National Renewable Energy Lab. (NREL), Golden, CO (United States)
- Univ. of Chicago, IL (United States); Argonne National Lab. (ANL), Argonne, IL (United States)
- Univ. of Chicago, IL (United States)
- Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
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.
- Research Organization:
- Argonne National Laboratory (ANL), Argonne, IL (United States); Energy Frontier Research Centers (EFRC) (United States). Center for Advanced Solar Photophysics (CASP); National Renewable Energy Laboratory (NREL), Golden, CO (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
- Grant/Contract Number:
- AC02-06CH11357; AC36-08GO28308
- OSTI ID:
- 1471985
- Alternate ID(s):
- OSTI ID: 1489380
- Report Number(s):
- NREL/JA--5900-71834
- Journal Information:
- ACS Nano, Journal Name: ACS Nano Journal Issue: 10 Vol. 12; ISSN 1936-0851
- Publisher:
- American Chemical Society (ACS)Copyright Statement
- Country of Publication:
- United States
- Language:
- English
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