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 language | English |
|---|---|
| Article number | 486 |
| Journal | Nature Communications |
| Volume | 2 |
| Issue number | 1 |
| DOIs | |
| Publication status | Published - 2011 |
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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 journal › Article
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TY - JOUR
T1 - Role of mid-gap states in charge transport and photoconductivity in semiconductor nanocrystal films
AU - Nagpal, Prashant
AU - Klimov, Victor I
PY - 2011
Y1 - 2011
N2 - 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.
AB - 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.
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U2 - 10.1038/ncomms1492
DO - 10.1038/ncomms1492
M3 - Article
C2 - 21952220
AN - SCOPUS:80053394412
VL - 2
JO - Nature Communications
JF - Nature Communications
SN - 2041-1723
IS - 1
M1 - 486
ER -