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Open structure ZnO/CdSe core/shell nanoneedle arrays for solar cells.

Chen Y, Wei L, Zhang G, Jiao J - Nanoscale Res Lett (2012)

Bottom Line: A uniform CdSe shell layer with a grain size of approximately several tens of nanometers was formed on the surface of ZnO nanoneedle cores after annealing at 400°C for 1.5 h.Fabricated solar cells based on these nanostructures exhibited a high short-circuit current density of about 10.5 mA/cm2 and an overall power conversion efficiency of 1.07% with solar illumination of 100 mW/cm2.Incident photo-to-current conversion efficiencies higher than 75% were also obtained.

View Article: PubMed Central - HTML - PubMed

Affiliation: School of Physics and State Key Laboratory of Crystal Materials, Shandong University, Jinan, 250100, People's Republic of China. cyx@sdu.edu.cn.

ABSTRACT
Open structure ZnO/CdSe core/shell nanoneedle arrays were prepared on a conducting glass (SnO2:F) substrate by solution deposition and electrochemical techniques. A uniform CdSe shell layer with a grain size of approximately several tens of nanometers was formed on the surface of ZnO nanoneedle cores after annealing at 400°C for 1.5 h. Fabricated solar cells based on these nanostructures exhibited a high short-circuit current density of about 10.5 mA/cm2 and an overall power conversion efficiency of 1.07% with solar illumination of 100 mW/cm2. Incident photo-to-current conversion efficiencies higher than 75% were also obtained.

No MeSH data available.


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Optical absorption (curve 1) and photoluminescence (curve 2) spectra of ZnO/CdSe core/shell nanoneedle arrays.
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Figure 3: Optical absorption (curve 1) and photoluminescence (curve 2) spectra of ZnO/CdSe core/shell nanoneedle arrays.

Mentions: The optical properties of the ZnO/CdSe core/shell nanostructures were investigated by absorption and PL measurements. Figure 3 shows the absorption and PL spectra of the ZnO/CdSe core/shell nanoneedle arrays. An optical bandgap of 1.71 eV is estimated for the CdSe layer from the absorption spectra, which is in good agreement with that of bulk CdSe. As the size of the CdSe grains is well above the CdSe Bohr exciton diameter (approximately 3 nm), no obvious blueshift caused by quantum confinement is observed. Similar to the cases of ZnO/ZnSe core/shell nanowires, a significant optical absorption is observed at wavelengths longer than the CdSe bandgap, which may arise from a spatially indirect transition or an interfacial transition coupling a hole state in CdSe shell with an electron state in the ZnO core. Strong bandgap excitonic emission at 1.68 eV upon excitation with a 532-nm laser is observed at room temperature. This high PL intensity indicates the high interior crystal quality and low defects of the CdSe shell layer, which is essential to reduce the recombination of the excited electron–hole pairs and increase the photocurrent of the solar cells. The high interior crystal quality of the CdSe shell layer is also confirmed by its HRTEM image (inset of Figure 1b).


Open structure ZnO/CdSe core/shell nanoneedle arrays for solar cells.

Chen Y, Wei L, Zhang G, Jiao J - Nanoscale Res Lett (2012)

Optical absorption (curve 1) and photoluminescence (curve 2) spectra of ZnO/CdSe core/shell nanoneedle arrays.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3475031&req=5

Figure 3: Optical absorption (curve 1) and photoluminescence (curve 2) spectra of ZnO/CdSe core/shell nanoneedle arrays.
Mentions: The optical properties of the ZnO/CdSe core/shell nanostructures were investigated by absorption and PL measurements. Figure 3 shows the absorption and PL spectra of the ZnO/CdSe core/shell nanoneedle arrays. An optical bandgap of 1.71 eV is estimated for the CdSe layer from the absorption spectra, which is in good agreement with that of bulk CdSe. As the size of the CdSe grains is well above the CdSe Bohr exciton diameter (approximately 3 nm), no obvious blueshift caused by quantum confinement is observed. Similar to the cases of ZnO/ZnSe core/shell nanowires, a significant optical absorption is observed at wavelengths longer than the CdSe bandgap, which may arise from a spatially indirect transition or an interfacial transition coupling a hole state in CdSe shell with an electron state in the ZnO core. Strong bandgap excitonic emission at 1.68 eV upon excitation with a 532-nm laser is observed at room temperature. This high PL intensity indicates the high interior crystal quality and low defects of the CdSe shell layer, which is essential to reduce the recombination of the excited electron–hole pairs and increase the photocurrent of the solar cells. The high interior crystal quality of the CdSe shell layer is also confirmed by its HRTEM image (inset of Figure 1b).

Bottom Line: A uniform CdSe shell layer with a grain size of approximately several tens of nanometers was formed on the surface of ZnO nanoneedle cores after annealing at 400°C for 1.5 h.Fabricated solar cells based on these nanostructures exhibited a high short-circuit current density of about 10.5 mA/cm2 and an overall power conversion efficiency of 1.07% with solar illumination of 100 mW/cm2.Incident photo-to-current conversion efficiencies higher than 75% were also obtained.

View Article: PubMed Central - HTML - PubMed

Affiliation: School of Physics and State Key Laboratory of Crystal Materials, Shandong University, Jinan, 250100, People's Republic of China. cyx@sdu.edu.cn.

ABSTRACT
Open structure ZnO/CdSe core/shell nanoneedle arrays were prepared on a conducting glass (SnO2:F) substrate by solution deposition and electrochemical techniques. A uniform CdSe shell layer with a grain size of approximately several tens of nanometers was formed on the surface of ZnO nanoneedle cores after annealing at 400°C for 1.5 h. Fabricated solar cells based on these nanostructures exhibited a high short-circuit current density of about 10.5 mA/cm2 and an overall power conversion efficiency of 1.07% with solar illumination of 100 mW/cm2. Incident photo-to-current conversion efficiencies higher than 75% were also obtained.

No MeSH data available.


Related in: MedlinePlus