Enhanced Multiple Exciton Generation in PbS|CdS Janus-like Heterostructured Nanocrystals
| Autor: | Boris D. Chernomordik, Rohan Singh, Ryan W. Crisp, Justin C. Johnson, Giulia Galli, Victor I. Klimov, Federico Giberti, Gregory F. Pach, Arthur J. Nozik, Matthew C. Beard, Márton Vörös, Daniel M. Kroupa |
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| Rok vydání: | 2018 |
| Předmět: |
Materials science
Photoluminescence Band gap Exciton Physics::Medical Physics General Physics and Astronomy 02 engineering and technology 010402 general chemistry 01 natural sciences law.invention Condensed Matter::Materials Science law Solar cell General Materials Science Spectroscopy business.industry General Engineering Condensed Matter::Mesoscopic Systems and Quantum Hall Effect 021001 nanoscience & nanotechnology 0104 chemical sciences Multiple exciton generation Nanocrystal Quantum dot Optoelectronics 0210 nano-technology business |
| Zdroj: | ACS nano. 12(10) |
| ISSN: | 1936-086X |
| Popis: | 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. |
| Databáze: | OpenAIRE |
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