Role of mid-gap states in charge transport and photoconductivity in semiconductor nanocrystal films

Prashant Nagpal, Victor I Klimov

Research output: Contribution to journalArticle

153 Citations (Scopus)

Abstract

Colloidal semiconductor nanocrystals have attracted significant interest for applications in solution-processable devices such as light-emitting diodes and solar cells. However, a poor understanding of charge transport in nanocrystal assemblies, specifically the relation between electrical conductance in dark and under light illumination, hinders their technological applicability. Here we simultaneously address the issues of 'dark' transport and photoconductivity in films of PbS nanocrystals, by incorporating them into optical field-effect transistors in which the channel conductance is controlled by both gate voltage and incident radiation. Spectrally resolved photoresponses of these devices reveal a weakly conductive mid-gap band that is responsible for charge transport in dark. The mechanism for conductance, however, changes under illumination when it becomes dominated by band-edge quantized states. In this case, the mid-gap band still has an important role as its occupancy (tuned by the gate voltage) controls the dynamics of band-edge charges.

Original languageEnglish
Article number486
JournalNature Communications
Volume2
Issue number1
DOIs
Publication statusPublished - 2011

Fingerprint

Quantum Dots
Photoconductivity
Lighting
photoconductivity
Nanoparticles
Nanocrystals
Charge transfer
nanocrystals
Semiconductor materials
Light
Equipment and Supplies
Energy gap
illumination
Radiation
Field effect transistors
Voltage control
Light emitting diodes
incident radiation
Solar cells
electric potential

ASJC Scopus subject areas

  • Biochemistry, Genetics and Molecular Biology(all)
  • Chemistry(all)
  • Physics and Astronomy(all)

Cite this

Role of mid-gap states in charge transport and photoconductivity in semiconductor nanocrystal films. / Nagpal, Prashant; Klimov, Victor I.

In: Nature Communications, Vol. 2, No. 1, 486, 2011.

Research output: Contribution to journalArticle

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