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Polarized near-infrared intersubband absorptions in CdSe colloidal quantum wells.

Nature communications (2019-10-06)
Benjamin T Diroll, Menglu Chen, Igor Coropceanu, Kali R Williams, Dmitri V Talapin, Philippe Guyot-Sionnest, Richard D Schaller

Colloidal quantum wells are two-dimensional materials grown with atomically-precise thickness that dictates their electronic structure. Although intersubband absorption in epitaxial quantum wells is well-known, analogous observations in non-epitaxial two-dimensional materials are sparse. Here we show that CdSe nanoplatelet quantum wells have narrow (30-200 meV), polarized intersubband absorption features when photoexcited or under applied bias, which can be tuned by thickness across the near-infrared (NIR) spectral window (900-1600 nm) inclusive of important telecommunications wavelengths. By examination of the optical absorption and polarization-resolved measurements, the NIR absorptions are assigned to electron intersubband transitions. Under photoexcitation, the intersubband features display hot carrier and Auger recombination effects similar to excitonic absorptions. Sequenced two-color photoexcitation permits the sub-picosecond modulation of the carrier temperature in such colloidal quantum wells. This work suggests that colloidal quantum wells may be promising building blocks for NIR technologies.

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Product Description

Oleic acid, technical grade, 90%
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Cadmium chloride, 99.99% trace metals basis
Tetrabutylammonium perchlorate, for electrochemical analysis, ≥99.0%
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