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Facile solution growth of vertically aligned ZnO nanorods sensitized with aqueous CdS and CdSe quantum dots for photovoltaic applications.

Luan C, Vaneski A, Susha AS, Xu X, Wang HE, Chen X, Xu J, Zhang W, Lee CS, Rogach AL, Zapien JA - Nanoscale Res Lett (2011)

Bottom Line: Vertically aligned single crystalline ZnO nanorod arrays, approximately 3 μm in length and 50-450 nm in diameter are grown by a simple solution approach on a Zn foil substrate.A thin Al2O3 layer deposited prior to quantum dot anchoring successfully acts as a barrier inhibiting electron recombination at the Zn/ZnO/electrolyte interface, resulting in power conversion efficiency of approximately 1% with an improved fill factor of 0.55.The in situ growth of ZnO nanorod arrays in a solution containing CdSe quantum dots provides better contact between two materials resulting in enhanced open circuit voltage.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Physics and Materials Science, City University of Hong Kong, Kowloon, Hong Kong SAR. andrey.rogach@cityu.edu.hk.

ABSTRACT
Vertically aligned single crystalline ZnO nanorod arrays, approximately 3 μm in length and 50-450 nm in diameter are grown by a simple solution approach on a Zn foil substrate. CdS and CdSe colloidal quantum dots are assembled onto ZnO nanorods array using water-soluble nanocrystals capped as-synthesized with a short-chain bifuncional linker thioglycolic acid. The solar cells co-sensitized with both CdS and CdSe quantum dots demonstrate superior efficiency compared with the cells using only one type of quantum dots. A thin Al2O3 layer deposited prior to quantum dot anchoring successfully acts as a barrier inhibiting electron recombination at the Zn/ZnO/electrolyte interface, resulting in power conversion efficiency of approximately 1% with an improved fill factor of 0.55. The in situ growth of ZnO nanorod arrays in a solution containing CdSe quantum dots provides better contact between two materials resulting in enhanced open circuit voltage.

No MeSH data available.


Kubelka-Munk diffuse reflectance absorption spectra of different samples. ZnO nanorods (open circle), ZnO nanorods decorated with CdS QDs (filled circle), ZnO nanorods decorated with CdSe QDs (open triangle), ZnO nanorods decorated with both CdS and CdSe QDs (filled triangle), and ZnO nanorods grown in an aqueous solution containing CdSe QDs (square). The absorbance spectra of the pristine CdS and CdSe QDs in aqueous solutions used for the NRAs treatment are shown in inset.
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Figure 4: Kubelka-Munk diffuse reflectance absorption spectra of different samples. ZnO nanorods (open circle), ZnO nanorods decorated with CdS QDs (filled circle), ZnO nanorods decorated with CdSe QDs (open triangle), ZnO nanorods decorated with both CdS and CdSe QDs (filled triangle), and ZnO nanorods grown in an aqueous solution containing CdSe QDs (square). The absorbance spectra of the pristine CdS and CdSe QDs in aqueous solutions used for the NRAs treatment are shown in inset.

Mentions: Figure 4 shows diffuse reflectance absorption spectra of ZnO NRAs prior and after decoration with CdS and CdSe QDs. The absorption in Kubelka-Munk units of the different ZnO electrodes sensitized with QDs has been extracted from their diffuse reflectance using the relation: F(R) = (1-R)2/2R, where R is the measured diffuse reflectance. This presentation allows a direct comparison of the amount of QDs adsorbed on each sample. The intrinsic absorption of ZnO nanorods can be seen as a steep increase below 400 nm. The QD decorated ZnO NRAs show increased absorption from 400 to 450 nm for CdS and from 400 to 520 nm for CdSe, respectively, with additional features around 425 and 480 nm due to the size-dependent electronic transitions of QDs. These spectral features closely match the absorption maxima of aqueous colloidal solutions of CdS and CdSe QDs, inset in Figure 4, with a slight red-shift which is likely caused by the close packing of QDs deposited on ZnO [26]. From the data of Figure 4, we estimate approximately the same amount of CdS and CdSe QDs adsorbed on ZnO NRAs, which is also expected owing to their same surface ligands and a similar concentration of nanoparticles in solution. The absorption features of the both QDs materials are present for samples sequentially immersed in CdS and in CdSe QD solutions. Remarkably, the in situ ZnO NRA growth in a bath solution containing CdSe QDs results in a strong absorption enhancement with respect to the NRAs decorated with QDs.


Facile solution growth of vertically aligned ZnO nanorods sensitized with aqueous CdS and CdSe quantum dots for photovoltaic applications.

Luan C, Vaneski A, Susha AS, Xu X, Wang HE, Chen X, Xu J, Zhang W, Lee CS, Rogach AL, Zapien JA - Nanoscale Res Lett (2011)

Kubelka-Munk diffuse reflectance absorption spectra of different samples. ZnO nanorods (open circle), ZnO nanorods decorated with CdS QDs (filled circle), ZnO nanorods decorated with CdSe QDs (open triangle), ZnO nanorods decorated with both CdS and CdSe QDs (filled triangle), and ZnO nanorods grown in an aqueous solution containing CdSe QDs (square). The absorbance spectra of the pristine CdS and CdSe QDs in aqueous solutions used for the NRAs treatment are shown in inset.
© Copyright Policy - open-access
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC3211429&req=5

Figure 4: Kubelka-Munk diffuse reflectance absorption spectra of different samples. ZnO nanorods (open circle), ZnO nanorods decorated with CdS QDs (filled circle), ZnO nanorods decorated with CdSe QDs (open triangle), ZnO nanorods decorated with both CdS and CdSe QDs (filled triangle), and ZnO nanorods grown in an aqueous solution containing CdSe QDs (square). The absorbance spectra of the pristine CdS and CdSe QDs in aqueous solutions used for the NRAs treatment are shown in inset.
Mentions: Figure 4 shows diffuse reflectance absorption spectra of ZnO NRAs prior and after decoration with CdS and CdSe QDs. The absorption in Kubelka-Munk units of the different ZnO electrodes sensitized with QDs has been extracted from their diffuse reflectance using the relation: F(R) = (1-R)2/2R, where R is the measured diffuse reflectance. This presentation allows a direct comparison of the amount of QDs adsorbed on each sample. The intrinsic absorption of ZnO nanorods can be seen as a steep increase below 400 nm. The QD decorated ZnO NRAs show increased absorption from 400 to 450 nm for CdS and from 400 to 520 nm for CdSe, respectively, with additional features around 425 and 480 nm due to the size-dependent electronic transitions of QDs. These spectral features closely match the absorption maxima of aqueous colloidal solutions of CdS and CdSe QDs, inset in Figure 4, with a slight red-shift which is likely caused by the close packing of QDs deposited on ZnO [26]. From the data of Figure 4, we estimate approximately the same amount of CdS and CdSe QDs adsorbed on ZnO NRAs, which is also expected owing to their same surface ligands and a similar concentration of nanoparticles in solution. The absorption features of the both QDs materials are present for samples sequentially immersed in CdS and in CdSe QD solutions. Remarkably, the in situ ZnO NRA growth in a bath solution containing CdSe QDs results in a strong absorption enhancement with respect to the NRAs decorated with QDs.

Bottom Line: Vertically aligned single crystalline ZnO nanorod arrays, approximately 3 μm in length and 50-450 nm in diameter are grown by a simple solution approach on a Zn foil substrate.A thin Al2O3 layer deposited prior to quantum dot anchoring successfully acts as a barrier inhibiting electron recombination at the Zn/ZnO/electrolyte interface, resulting in power conversion efficiency of approximately 1% with an improved fill factor of 0.55.The in situ growth of ZnO nanorod arrays in a solution containing CdSe quantum dots provides better contact between two materials resulting in enhanced open circuit voltage.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Physics and Materials Science, City University of Hong Kong, Kowloon, Hong Kong SAR. andrey.rogach@cityu.edu.hk.

ABSTRACT
Vertically aligned single crystalline ZnO nanorod arrays, approximately 3 μm in length and 50-450 nm in diameter are grown by a simple solution approach on a Zn foil substrate. CdS and CdSe colloidal quantum dots are assembled onto ZnO nanorods array using water-soluble nanocrystals capped as-synthesized with a short-chain bifuncional linker thioglycolic acid. The solar cells co-sensitized with both CdS and CdSe quantum dots demonstrate superior efficiency compared with the cells using only one type of quantum dots. A thin Al2O3 layer deposited prior to quantum dot anchoring successfully acts as a barrier inhibiting electron recombination at the Zn/ZnO/electrolyte interface, resulting in power conversion efficiency of approximately 1% with an improved fill factor of 0.55. The in situ growth of ZnO nanorod arrays in a solution containing CdSe quantum dots provides better contact between two materials resulting in enhanced open circuit voltage.

No MeSH data available.