Dual-color electroluminescence from dot-in-bulk nanocrystals

Sergio Brovelli, Wan Ki Bae, Christophe Galland, Umberto Giovanella, Francesco Meinardi, Victor I Klimov

Research output: Contribution to journalArticle

40 Citations (Scopus)

Abstract

The emission color from colloidal semiconductor nanocrystals (NCs) is usually tuned through control of particle size, while multicolor emission is obtained by mixing NCs of different sizes within an emissive layer. Here, we demonstrate that recently introduced "dot-in-bulk" (DiB) nanocrystals can emit two-color light under both optical excitation and electrical injection. We show that the effective emission color can be controlled by adjusting the relative amplitudes of the core and shell emission bands via the intensity of optical excitation or applied bias in the cases of photoluminescence (PL) and electroluminescence (EL), respectively. To investigate the role of nonradiative carrier losses due to trapping at intragap states, we incorporate DiB NCs into functional light-emitting diodes and study their PL as a function of applied bias below the EL excitation threshold. We show that voltage-dependent changes in core and shell emissions are not due to the applied electric field but rather arise from the transfer of charges between the anode and the NC intragap trap sites. The changes in the occupancy of trap states can be described in terms of the raising (lowering) of the Fermi level for reverse (direct) bias. We find that the applied voltage affects the overall PL intensity primarily via the electron-trapping channel while bias-induced changes in hole-trapping play a less significant role, limited to a weak effect on core emission.

Original languageEnglish
Pages (from-to)486-494
Number of pages9
JournalNano Letters
Volume14
Issue number2
DOIs
Publication statusPublished - Feb 12 2014

Fingerprint

Electroluminescence
electroluminescence
Nanocrystals
nanocrystals
Color
color
Photoluminescence
Photoexcitation
trapping
photoluminescence
traps
excitation
Electric potential
Fermi level
electric potential
Light emitting diodes
Anodes
Particle size
Electric fields
Semiconductor materials

Keywords

  • core/shell heterostructure
  • dual emission
  • electroluminescence
  • light-emitting diode
  • Nanocrystal quantum dot
  • surface defect

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Bioengineering
  • Chemistry(all)
  • Materials Science(all)
  • Mechanical Engineering

Cite this

Brovelli, S., Bae, W. K., Galland, C., Giovanella, U., Meinardi, F., & Klimov, V. I. (2014). Dual-color electroluminescence from dot-in-bulk nanocrystals. Nano Letters, 14(2), 486-494. https://doi.org/10.1021/nl403478s

Dual-color electroluminescence from dot-in-bulk nanocrystals. / Brovelli, Sergio; Bae, Wan Ki; Galland, Christophe; Giovanella, Umberto; Meinardi, Francesco; Klimov, Victor I.

In: Nano Letters, Vol. 14, No. 2, 12.02.2014, p. 486-494.

Research output: Contribution to journalArticle

Brovelli, S, Bae, WK, Galland, C, Giovanella, U, Meinardi, F & Klimov, VI 2014, 'Dual-color electroluminescence from dot-in-bulk nanocrystals', Nano Letters, vol. 14, no. 2, pp. 486-494. https://doi.org/10.1021/nl403478s
Brovelli S, Bae WK, Galland C, Giovanella U, Meinardi F, Klimov VI. Dual-color electroluminescence from dot-in-bulk nanocrystals. Nano Letters. 2014 Feb 12;14(2):486-494. https://doi.org/10.1021/nl403478s
Brovelli, Sergio ; Bae, Wan Ki ; Galland, Christophe ; Giovanella, Umberto ; Meinardi, Francesco ; Klimov, Victor I. / Dual-color electroluminescence from dot-in-bulk nanocrystals. In: Nano Letters. 2014 ; Vol. 14, No. 2. pp. 486-494.
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