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Doping graphene films via chemically mediated charge transfer.

Ishikawa R, Bando M, Morimoto Y, Sandhu A - Nanoscale Res Lett (2011)

Bottom Line: Graphene-based TCFs have attracted a lot of attention because of their high electrical conductivity, transparency, and low cost.Notably, TCNQ is well known as a powerful electron accepter and is expected to favor electron transfer from graphene into TCNQ molecules, thereby leading to p-type doping of graphene films.Small amounts of TCNQ drastically improved the resistivity without degradation of optical transparency.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Electrical and Electronic Engineering, Tokyo Institute of Technology, 2-12-1 O-okayama, Meguro, Tokyo 152-8552, Japan. ishikawa.r.ab@m.titech.ac.jp.

ABSTRACT
Transparent conductive films (TCFs) are critical components of a myriad of technologies including flat panel displays, light-emitting diodes, and solar cells. Graphene-based TCFs have attracted a lot of attention because of their high electrical conductivity, transparency, and low cost. Carrier doping of graphene would potentially improve the properties of graphene-based TCFs for practical industrial applications. However, controlling the carrier type and concentration of dopants in graphene films is challenging, especially for the synthesis of p-type films. In this article, a new method for doping graphene using the conjugated organic molecule, tetracyanoquinodimethane (TCNQ), is described. Notably, TCNQ is well known as a powerful electron accepter and is expected to favor electron transfer from graphene into TCNQ molecules, thereby leading to p-type doping of graphene films. Small amounts of TCNQ drastically improved the resistivity without degradation of optical transparency. Our carrier doping method based on charge transfer has a huge potential for graphene-based TCFs.

No MeSH data available.


Physical property of fabricated graphene films. (a) Optical transmittance spectra, (b) Summarized optical and electrical properties.
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Figure 5: Physical property of fabricated graphene films. (a) Optical transmittance spectra, (b) Summarized optical and electrical properties.

Mentions: Figure 4a shows photograph of fabricated graphene films on glass substrates at various spray volumes. SEM images of fabricated graphene films revealed them to be continuous and uniform (Figure 4b). Figure 5a shows the optical transmittance spectra of these fabricated graphene films, and the transmittance decreased for all wavelength ranges as the spray volume increased. Optical and electrical properties are summarized in Figure 5b. Sheet resistance of minimum spray volume sample was too high to be measured by our analyzer. The graphene films obtained in this study had a sheet resistance as high as 1 × 106 Ω/square with a transparency of 88% at 550 nm. Such a sheet resistance was the lowest obtained compared with previously reported chemically derived graphene films as deposited [6,18]. Post-annealing treatment was expected to improve the performance of our graphene films due to removal of residual solvent and oxygen-containing functional groups on RGO. Actually, Becerril et al. [19] obtained the highest performance in chemically derived graphene films through high-temperature annealing in vacuum. However, no post-annealing treatment on our graphene films was conducted, since the focus was on an inexpensive fabrication procedure without any vacuum systems.


Doping graphene films via chemically mediated charge transfer.

Ishikawa R, Bando M, Morimoto Y, Sandhu A - Nanoscale Res Lett (2011)

Physical property of fabricated graphene films. (a) Optical transmittance spectra, (b) Summarized optical and electrical properties.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3211156&req=5

Figure 5: Physical property of fabricated graphene films. (a) Optical transmittance spectra, (b) Summarized optical and electrical properties.
Mentions: Figure 4a shows photograph of fabricated graphene films on glass substrates at various spray volumes. SEM images of fabricated graphene films revealed them to be continuous and uniform (Figure 4b). Figure 5a shows the optical transmittance spectra of these fabricated graphene films, and the transmittance decreased for all wavelength ranges as the spray volume increased. Optical and electrical properties are summarized in Figure 5b. Sheet resistance of minimum spray volume sample was too high to be measured by our analyzer. The graphene films obtained in this study had a sheet resistance as high as 1 × 106 Ω/square with a transparency of 88% at 550 nm. Such a sheet resistance was the lowest obtained compared with previously reported chemically derived graphene films as deposited [6,18]. Post-annealing treatment was expected to improve the performance of our graphene films due to removal of residual solvent and oxygen-containing functional groups on RGO. Actually, Becerril et al. [19] obtained the highest performance in chemically derived graphene films through high-temperature annealing in vacuum. However, no post-annealing treatment on our graphene films was conducted, since the focus was on an inexpensive fabrication procedure without any vacuum systems.

Bottom Line: Graphene-based TCFs have attracted a lot of attention because of their high electrical conductivity, transparency, and low cost.Notably, TCNQ is well known as a powerful electron accepter and is expected to favor electron transfer from graphene into TCNQ molecules, thereby leading to p-type doping of graphene films.Small amounts of TCNQ drastically improved the resistivity without degradation of optical transparency.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Electrical and Electronic Engineering, Tokyo Institute of Technology, 2-12-1 O-okayama, Meguro, Tokyo 152-8552, Japan. ishikawa.r.ab@m.titech.ac.jp.

ABSTRACT
Transparent conductive films (TCFs) are critical components of a myriad of technologies including flat panel displays, light-emitting diodes, and solar cells. Graphene-based TCFs have attracted a lot of attention because of their high electrical conductivity, transparency, and low cost. Carrier doping of graphene would potentially improve the properties of graphene-based TCFs for practical industrial applications. However, controlling the carrier type and concentration of dopants in graphene films is challenging, especially for the synthesis of p-type films. In this article, a new method for doping graphene using the conjugated organic molecule, tetracyanoquinodimethane (TCNQ), is described. Notably, TCNQ is well known as a powerful electron accepter and is expected to favor electron transfer from graphene into TCNQ molecules, thereby leading to p-type doping of graphene films. Small amounts of TCNQ drastically improved the resistivity without degradation of optical transparency. Our carrier doping method based on charge transfer has a huge potential for graphene-based TCFs.

No MeSH data available.