Suppression of auger recombination in ""giant"" core/shell nanocrystals

Journal Article · Thu Jan 01 04:00:00 EST 2009 · Science

OSTI ID:956462

Garcia Santamaria, Florencio ^[1]; Vela, Javier ^[1]; Schaller, Richard D ^[1]; Hollingsworth, Jennifer A ^[1]; Klimov, Victor I ^[1]; Chen, Yongfen ^[2]

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1. Los Alamos National Laboratory
2. NON LANL

Many potential applications of semiconductor nanocrystals are hindered by nonradiative Auger recombination wherein the electron-hole (exciton) recombination energy is transferred to a third charge carrier. This process severely limits the lifetime and bandwidth of optical gain, leads to large nonradiative losses in light emitting diodes and photovoltaic cells, and is believed to be responsible for intermittency ('blinking') of emission from single nanocrystals. The development of nanostructures in which Auger recombination is suppressed has been a longstanding goal in colloidal nanocrystal research. Here, we demonstrate that such suppression is possible using so-called 'giant' nanocrystals that consist of a small CdSe core and a thick CdS shell. These nanostructures exhibit a very long biexciton lifetime ({approx}10 ns) that is likely dominated by radiative decay instead of non-radiative Auger recombination. As a result of suppressed Auger recombination, even high-order multiexcitons exhibit high emission efficiencies, which allows us to demonstrate optical amplification with an extraordinarily large bandwidth (>500 me V) and record low excitation thresholds.

• Research Organization: Los Alamos National Laboratory (LANL)
• Sponsoring Organization: DOE
• DOE Contract Number: AC52-06NA25396
• OSTI ID: 956462
• Report Number(s): LA-UR-09-01139; LA-UR-09-1139
• Journal Information: Science, Journal Name: Science; ISSN 0193-4511; ISSN SCEHDK
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
AMPLIFICATION
CHARGE CARRIERS
EXCITATION
EXCITONS
LIFETIME
LIGHT EMITTING DIODES
NANOSTRUCTURES
PHOTOVOLTAIC CELLS
RADIATIVE DECAY
RECOMBINATION