Abstract
Optical gain from colloidal quantum dots has been desired for several decades since their discovery. While gain from multiexcitations is by now well-established, nonradiative Auger recombination limits the lifetime of such population inversion in quantum dots. CdSe cores isovalently doped by one to few Te atoms capped with rod-shaped CdS are examined as a candidate system for enhanced stimulated emission properties. Emission depletion spectroscopy shows a behavior characteristic of 3-level gain systems in these quantum dots. This implies complete removal of the 2-fold degeneracy of the lowest energy electronic excitation due to the large repulsive exciton-exciton interaction in the doubly excited state. Using emission depletion measurements of the trap-associated emission from poorly passivated CdS quantum dots, we show that 3-level characteristics are typical of emission resulting from a band edge to trap state transition, but reveal subtle differences between the two systems. These results allow for unprecedented observation of long-lived population inversion from singly excited quantum dots.
| Original language | English |
|---|---|
| Pages (from-to) | 817-824 |
| Number of pages | 8 |
| Journal | ACS Nano |
| Volume | 9 |
| Issue number | 1 |
| DOIs | |
| Publication status | Published - Jan 27 2015 |
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Keywords
- isovalent doping
- optical gain
- quantum dots
- stimulated emission
- trap emission
ASJC Scopus subject areas
- Engineering(all)
- Materials Science(all)
- Physics and Astronomy(all)
Cite this
Long-lived population inversion in isovalently doped quantum dots. / Lahad, Ohr; Meir, Noga; Pinkas, Iddo; Oron, Dan.
In: ACS Nano, Vol. 9, No. 1, 27.01.2015, p. 817-824.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Long-lived population inversion in isovalently doped quantum dots
AU - Lahad, Ohr
AU - Meir, Noga
AU - Pinkas, Iddo
AU - Oron, Dan
PY - 2015/1/27
Y1 - 2015/1/27
N2 - Optical gain from colloidal quantum dots has been desired for several decades since their discovery. While gain from multiexcitations is by now well-established, nonradiative Auger recombination limits the lifetime of such population inversion in quantum dots. CdSe cores isovalently doped by one to few Te atoms capped with rod-shaped CdS are examined as a candidate system for enhanced stimulated emission properties. Emission depletion spectroscopy shows a behavior characteristic of 3-level gain systems in these quantum dots. This implies complete removal of the 2-fold degeneracy of the lowest energy electronic excitation due to the large repulsive exciton-exciton interaction in the doubly excited state. Using emission depletion measurements of the trap-associated emission from poorly passivated CdS quantum dots, we show that 3-level characteristics are typical of emission resulting from a band edge to trap state transition, but reveal subtle differences between the two systems. These results allow for unprecedented observation of long-lived population inversion from singly excited quantum dots.
AB - Optical gain from colloidal quantum dots has been desired for several decades since their discovery. While gain from multiexcitations is by now well-established, nonradiative Auger recombination limits the lifetime of such population inversion in quantum dots. CdSe cores isovalently doped by one to few Te atoms capped with rod-shaped CdS are examined as a candidate system for enhanced stimulated emission properties. Emission depletion spectroscopy shows a behavior characteristic of 3-level gain systems in these quantum dots. This implies complete removal of the 2-fold degeneracy of the lowest energy electronic excitation due to the large repulsive exciton-exciton interaction in the doubly excited state. Using emission depletion measurements of the trap-associated emission from poorly passivated CdS quantum dots, we show that 3-level characteristics are typical of emission resulting from a band edge to trap state transition, but reveal subtle differences between the two systems. These results allow for unprecedented observation of long-lived population inversion from singly excited quantum dots.
KW - isovalent doping
KW - optical gain
KW - quantum dots
KW - stimulated emission
KW - trap emission
UR - http://www.scopus.com/inward/record.url?scp=84921712718&partnerID=8YFLogxK
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U2 - 10.1021/nn506404n
DO - 10.1021/nn506404n
M3 - Article
VL - 9
SP - 817
EP - 824
JO - ACS Nano
JF - ACS Nano
SN - 1936-0851
IS - 1
ER -