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Type: Artigo
Title: Enhanced carrier multiplication in engineered quasi-type-II quantum dots
Author: Cirloganu, C. M.
Padilha, L. A.
Lin, Q. L.
Makarov, N. S.
Velizhanin, K. A.
Luo, H. M.
Robel, I.
Pietryga, J. M.
Klimov, V. I.
Abstract: One process limiting the performance of solar cells is rapid cooling (thermalization) of hot carriers generated by higher-energy solar photons. In principle, the thermalization losses can be reduced by converting the kinetic energy of energetic carriers into additional electron-hole pairs via carrier multiplication (CM). While being inefficient in bulk semiconductors this process is enhanced in quantum dots, although not sufficiently high to considerably boost the power output of practical devices. Here we demonstrate that thick-shell PbSe/CdSe nanostructures can show almost a fourfold increase in the CM yield over conventional PbSe quantum dots, accompanied by a considerable reduction of the CM threshold. These structures enhance a valence-band CM channel due to effective capture of energetic holes into long-lived shell-localized states. The attainment of the regime of slowed cooling responsible for CM enhancement is indicated by the development of shell-related emission in the visible observed simultaneously with infrared emission from the core.
Subject: Nanocristais
Pontos quânticos
Quantum dots
Country: Reino Unido
Editor: Nature Publishing Group
Rights: aberto
Identifier DOI: 10.1038/ncomms5148
Date Issue: 2014
Appears in Collections:IFGW - Artigos e Outros Documentos

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