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.
Highlights
As an n-type semiconductor with a direct and wide bandgap of 3.3 eV, ZnO is an attractive material for a variety of applications ranging from ultraviolet lasers [1] and sensors [2] to field-emission devices [3]
We demonstrate an efficient coverage of ZnO nanorod arrays (NRAs) grown on a Zn foil substrate by a simple solution approach with CdS or CdSe quantum dots (QDs) using water-soluble nanocrystals capped as-synthesized with a short-chain bifuncional thioglycolic acid (TGA) linker
Higher magnification of a single ZnO nanorod by transmission electron microscope (TEM) is shown in Figure 1c; the corresponding fast Fourier transform (FFT) pattern indicates that the hexagonal ZnO nanorod grows along the [001] direction
Summary
As an n-type semiconductor with a direct and wide bandgap of 3.3 eV, ZnO is an attractive material for a variety of applications ranging from ultraviolet lasers [1] and sensors [2] to field-emission devices [3]. We demonstrate an efficient coverage of ZnO nanorod arrays (NRAs) grown on a Zn foil substrate by a simple solution approach with CdS or CdSe QDs using water-soluble nanocrystals capped as-synthesized with a short-chain bifuncional TGA linker. The deposition temperature was 150°C and the expected growth rate was 0.91 Å/cycle; a total of 15 cycles were carried out to deposit an ultrathin Al2O3 layer on the surface of selected ZnO NRAs prior to the decoration with QDs. Sensitization of ZnO NRAs with QDs Substrates with vertically aligned ZnO NRAs were immersed in aqueous colloidal solutions of CdS or CdSe QDs (pH 9.5, particle concentration of approximately 10-5 M) for 4 h at room temperature, and subsequently dried at 90°C for several minutes. The assembled cells were illuminated using a solar simulator at AM 1.5 G, where the light intensity was adjusted with a NREL-calibrated Si solar cell with a KG-5 filter to 1 sun intensity (100 mWcm-2)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
