Degenerately n-Doped Colloidal PbSe Quantum Dots: Band Assignments and Electrostatic Effects.
Nano Lett
; 18(6): 3893-3900, 2018 06 13.
Article
en En
| MEDLINE
| ID: mdl-29763319
We present a spectroscopic study of colloidal PbSe quantum dots (QDs) that have been photodoped to introduce excess delocalized conduction-band (CB) electrons. High-quality absorption spectra are obtained for these degenerately doped QDs with excess electron concentrations up to â¼1020 cm-3. At the highest doping levels, electrons have completely filled the 1Se orbitals of the CB and partially populated the higher-energy 1Pe orbitals. Spectroscopic changes observed as a function of carrier concentration permit an unambiguous assignment of the second excitonic absorption maximum to 1Ph-1Pe transitions. At intermediate doping levels, a clear absorption feature appears between the first two excitonic maxima that is attributable to parity-forbidden 1Sh,e-1Pe,h excitations, which become observable because of electrostatic symmetry breaking. Redshifts of the main excitonic absorption features with increased carrier concentration are also analyzed. The Coulomb stabilization energies of both the 1Sh-1Se and 1Ph-1Pe excitons in n-doped PbSe QDs are remarkably similar to those observed for multiexcitons with the same electron count. The origins of these redshifts are discussed.
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01-internacional
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MEDLINE
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En
Revista:
Nano Lett
Año:
2018
Tipo del documento:
Article
País de afiliación:
Estados Unidos
Pais de publicación:
Estados Unidos