Yanlong Meng

Structure and photoluminescence properties of Fe-doped ZnO thin films

Zn1−xFexO films were prepared by the radio-frequency (rf) magnetron sputtering technique on n-Si substrates with a composite target of a ceramic polycrystalline ZnO containing several Fe pieces on the surface. X-ray photoelectron spectroscopy study of the Zn1−xFexO films shows that Fe in the as-deposited film exists mainly in the form of Fe2+. And x-ray diffraction spectra show that all the films exhibited c-axis orientation. The room temperature photoluminescence (PL) properties of the Zn1−xFexO films were also discussed. Two obvious PL peaks appear at 378 nm and 414 nm, respectively. It is interesting that there is a tendency of redshift for the peak at 378 nm and that the PL intensity increases slightly for the peak at 414 nm as the Fe concentration increases. Discussions have been given to explain the different phenomena.

Influence of nanowires length on performance of crystalline silicon solar cell

Silicon-nanowire (Si-NW) array, prepared by an electroless chemical-etching method, shows excellent optical antireflection property over a wide spectral bandwidth. The influence of the wire length on the optical antireflection property and the solar cell performance were studied for both the Si-NW array solar cells and the planar solar cells. The reflectance of NWs solar cells is almost invariable and much lower than that of the planar solar cells but the performance of planar solar cells is the best. Results show the performance of NWs solar cells is strongly affected by some other factors such as surface passivation and electrode-contact property.

Electrode-contact enhancement in silicon nanowire-array-textured solar cells

In the case of the silicon (Si) nanowire (NW)-array-textured solar cells, the electrode-contact enhancement has been achieved using a simple and convenient double-step diffusion process to form a highly doped N+ region at the tips of a Si-NW array. The series resistance can be effectively reduced, leading to an increase in the short-circuit current density in the cell. We have studied the physical mechanism of the impact of an increase in doping level at the tips of a Si-NW array on the electrode-contact property, which would benefit in realizing an improvement in cell performance in such a nanostructure solar cell.

Antireflection properties and solar cell application of silicon nanostructures

Silicon nanowire (Si NW) arrays were fabricated on polished and pyramids textured mono-crystalline Si (mc-Si) using an aqueous chemical etching method. The Si NWs and a hybrid texture of NWs and pyramids both show strong anti-reflectance properties in the wavelength region of 300–1000 nm, with the minimum average reflectance of 2.52% and 8%, respectively. The above two nanostructures were fabricated on mc-Si solar cells with the area of 125×125 mm2. Then the influences of Si NWs and hybrid textures on the performances of mc-Si solar cells created using different fabrication processes were analyzed by internal quantum efficiency measurement and by systematical comparisons of efficiency, filling factor, open circuit voltage and short-circuit current. Passivation is found to be essential for the hybrid textured solar cells, and the average open circuit voltage can be improved by 7% after a passivation layer was deposited. The short circuit current could be increased when Si NWs were fabricated on a substrate...

Maskless fabrication of selectively sized silicon nanostructures for solar cell application

A two-step maskless method was used to synthesize silicon nanostructures. In the first step, silver nanoparticles were formed through rapid thermal annealing of silver thin films. The temperature, duration of annealing, and initial thickness of the silver film jointly determined the distribution and diameter of silver particles. In the next step, silicon nanostructures were created using silver catalyzed etching in HF/H2O2. The experiment confirmed that the final sizes of the nanostructures corresponded to the diameters of the silver particles. Further, silicon nanostructure-textured solar cells were manufactured and tested. The surface-reflection ratio of the cells can be decreased to 5% in the 300–1000 nm wavelength range. The current-voltage and quantum efficiency measurements also reveal that silicon nanostructure-textured solar cells exhibit considerable light trapping enhancement. The results also indicate that effective passivation and electrode contact are important for those cells.