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Microscopic observation of dye molecules for solar cells on a titania surface.

Koshiya S, Yamashita S, Kimoto K - Sci Rep (2016)

Bottom Line: A single dye molecule on the titania nanosheet was visualized for the first time.The quantitative STEM images revealed an inhomogeneous dye-molecule distribution at the early stage of its absorption, i.e., the aggregation of the dye molecules.The majority of the titania surface was not covered by dye molecules, suggesting that optimization of the dye molecule distribution could yield further improvement of the DSC conversion efficiencies.

View Article: PubMed Central - PubMed

Affiliation: Surface Physics and Structure Unit, National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan.

ABSTRACT
The lateral distribution and coverage of Ru-based dye molecules, which are used for dye-sensitized solar cells (DSCs), were directly examined on a titania surface using high-resolution scanning transmission electron microscopy (STEM). The clean surface of a free-standing titania nanosheet was first confirmed with atomic resolution, and then, the nanosheet was used as a substrate. A single dye molecule on the titania nanosheet was visualized for the first time. The quantitative STEM images revealed an inhomogeneous dye-molecule distribution at the early stage of its absorption, i.e., the aggregation of the dye molecules. The majority of the titania surface was not covered by dye molecules, suggesting that optimization of the dye molecule distribution could yield further improvement of the DSC conversion efficiencies.

No MeSH data available.


Related in: MedlinePlus

Dye molecule distribution map.(a) ADF image at low magnification. (b) Dye molecule distribution map. The QADF scales in (a,b) were set in the same range of 0–0.63%. The coverage of N3 dye molecules is indicated using the ADF contrasts of the monolayer titania nanosheet (0.25%) and N3 dye molecule (0.076%).
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f4: Dye molecule distribution map.(a) ADF image at low magnification. (b) Dye molecule distribution map. The QADF scales in (a,b) were set in the same range of 0–0.63%. The coverage of N3 dye molecules is indicated using the ADF contrasts of the monolayer titania nanosheet (0.25%) and N3 dye molecule (0.076%).

Mentions: It is also observed that the distribution of dye molecules is inhomogeneous; for instance, brighter domains are observed at the corners of Fig. 3. Next, we analyse the coverage of molecules including the bright domains. Figure 4a presents a low-magnification ADF image. The monolayer and bilayer titanium oxide nanosheets can be observed in the bottom and top regions, respectively. To clarify the coverage of attached dye molecules, the experimental ADF images were converted into a coloured image, assuming a monolayer titania nanosheet contrast of 0.25% (see Fig. 1a) and a single-molecule coverage contrast of 0.076%, as shown in Fig. 4b. To reduce shot noises, Fig. 4a was smoothed using a 7 × 7 pixel kernel, and the coverage of dye molecules can be recognized in Fig. 4b. The coverage of the majority of the surface was less than 1 molecule, and there were many aggregates with diameters of a few tens of nanometres with multi-molecule coverage. This microscopic observation of the dye-molecule distributions could accelerate the understanding of the attaching mechanism.


Microscopic observation of dye molecules for solar cells on a titania surface.

Koshiya S, Yamashita S, Kimoto K - Sci Rep (2016)

Dye molecule distribution map.(a) ADF image at low magnification. (b) Dye molecule distribution map. The QADF scales in (a,b) were set in the same range of 0–0.63%. The coverage of N3 dye molecules is indicated using the ADF contrasts of the monolayer titania nanosheet (0.25%) and N3 dye molecule (0.076%).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4834531&req=5

f4: Dye molecule distribution map.(a) ADF image at low magnification. (b) Dye molecule distribution map. The QADF scales in (a,b) were set in the same range of 0–0.63%. The coverage of N3 dye molecules is indicated using the ADF contrasts of the monolayer titania nanosheet (0.25%) and N3 dye molecule (0.076%).
Mentions: It is also observed that the distribution of dye molecules is inhomogeneous; for instance, brighter domains are observed at the corners of Fig. 3. Next, we analyse the coverage of molecules including the bright domains. Figure 4a presents a low-magnification ADF image. The monolayer and bilayer titanium oxide nanosheets can be observed in the bottom and top regions, respectively. To clarify the coverage of attached dye molecules, the experimental ADF images were converted into a coloured image, assuming a monolayer titania nanosheet contrast of 0.25% (see Fig. 1a) and a single-molecule coverage contrast of 0.076%, as shown in Fig. 4b. To reduce shot noises, Fig. 4a was smoothed using a 7 × 7 pixel kernel, and the coverage of dye molecules can be recognized in Fig. 4b. The coverage of the majority of the surface was less than 1 molecule, and there were many aggregates with diameters of a few tens of nanometres with multi-molecule coverage. This microscopic observation of the dye-molecule distributions could accelerate the understanding of the attaching mechanism.

Bottom Line: A single dye molecule on the titania nanosheet was visualized for the first time.The quantitative STEM images revealed an inhomogeneous dye-molecule distribution at the early stage of its absorption, i.e., the aggregation of the dye molecules.The majority of the titania surface was not covered by dye molecules, suggesting that optimization of the dye molecule distribution could yield further improvement of the DSC conversion efficiencies.

View Article: PubMed Central - PubMed

Affiliation: Surface Physics and Structure Unit, National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan.

ABSTRACT
The lateral distribution and coverage of Ru-based dye molecules, which are used for dye-sensitized solar cells (DSCs), were directly examined on a titania surface using high-resolution scanning transmission electron microscopy (STEM). The clean surface of a free-standing titania nanosheet was first confirmed with atomic resolution, and then, the nanosheet was used as a substrate. A single dye molecule on the titania nanosheet was visualized for the first time. The quantitative STEM images revealed an inhomogeneous dye-molecule distribution at the early stage of its absorption, i.e., the aggregation of the dye molecules. The majority of the titania surface was not covered by dye molecules, suggesting that optimization of the dye molecule distribution could yield further improvement of the DSC conversion efficiencies.

No MeSH data available.


Related in: MedlinePlus