High-efficiency optical gain in type-II semiconductor nanocrystals of alloyed colloidal quantum wells
Date
2017Source Title
Journal of Physical Chemistry Letters
Print ISSN
1948-7185
Publisher
American Chemical Society
Volume
8
Issue
21
Pages
5317 - 5324
Language
English
Type
ArticleItem Usage Stats
218
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views
345
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Abstract
Colloidal nanocrystals having controlled size, tailored shape, and tuned composition have been explored for optical gain and lasing. Among these, nanocrystals having Type-II electronic structure have been introduced toward low-threshold gain. However, to date, their performance has remained severely limited due to diminishing oscillator strength and modest absorption cross-section. Overcoming these problems, here we realize highly efficient optical gain in Type-II nanocrystals by using alloyed colloidal quantum wells. With composition-tuned core/alloyed-crown CdSe/CdSexTe1-x quantum wells, we achieved amplified spontaneous emission thresholds as low as 26 μJ/cm2, long optical gain lifetimes (τgain ≈ 400 ps), and high modal gain coefficients (gmodal ≈ 930 cm-1). We uncover that the optical gain in these Type-II quantum wells arises from the excitations localized to the alloyed-crown region that are electronically coupled to the charge-transfer state. These alloyed heteronanostructures exhibiting remarkable optical gain performance are expected to be highly appealing for future display and lighting technologies.
Keywords
Cadmium compoundsCharge transfer
Electronic structure
Nanocrystals
Optical gain
Quantum theory
Absorption cross sections
Amplified spontaneous emissions
Charge transfer state
Colloidal nanocrystals
Colloidal quantum wells
Hetero-nanostructures
Semiconductor nanocrystals
Type-II quantum wells
Semiconductor quantum wells
Permalink
http://hdl.handle.net/11693/37292Published Version (Please cite this version)
http://dx.doi.org/10.1021/acs.jpclett.7b02367Collections
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