Enhancing Solar Cell Efficiencies through 1-D Nanostructures

The current global energy problem can be attributed to insufficient fossil fuel supplies and excessive greenhouse gas emissions resulting from increasing fossil fuel consumption. The huge demand for clean energy potentially can be met by solar-to-electricity conversions. The large-scale use of solar energy is not occurring due to the high cost and inadequate efficiencies of existing solar cells. Nanostructured materials have offered new opportunities to design more efficient solar cells, particularly one-dimensional (1-D) nanomaterials for enhancing solar cell efficiencies. These 1-D nanostructures, including nanotubes, nanowires, and nanorods, offer significant opportunities to improve efficiencies of solar cells by facilitating photon absorption, electron transport, and electron collection; however, tremendous challenges must be conquered before the large-scale commercialization of such cells. This review specifically focuses on the use of 1-D nanostructures for enhancing solar cell efficiencies. Other nanostructured solar cells or solar cells based on bulk materials are not covered in this review. Major topics addressed include dye-sensitized solar cells, quantum-dot-sensitized solar cells, and p-n junction solar cells.     

氧化镓钠米带的制备研究

纳米带是继纳米线、纳米管之后,最新报道的又一种准一维纳米结构。文中介绍了Ga2O3纳米带制备的新方法。这种方法与首次报道的纳米带的生长方法有很大不同。用扫描电子显微镜和透射电子显微镜对产物形貌进行了分析,纳米带宽约500nm,厚度约10nm,宽度/厚度比大于20。选区电子衍射（SAED）分析表明,产物是纯净的Ga2O3单晶。实验还发现了一些特殊形态的纳米结构,如纳米片等,证明了纳米带是一种常见并稳定存在的形态。最后,根据实验现象对纳米带的生长机制进行了初步的分析与讨论。     

Synthesis of flower-like CuO nanostructures via a simple hydrolysis route

We describe a facile route for the synthesis of flower-like CuO nanostructures by hydrolyzing of Cu(OAc)₂ solution without any surfactants. SEM and TEM observations indicate that the CuO products are composed of microspheres with diameters of 0.4-0.8 μm. The microspheres are in fact built from small needle-like nanocrystals with diameters of 10-15 nm. The method provides a convenient, low-cost, nontoxic route for the synthesis of nanostructures of oxide materials, and it is important for exploring oxide-based nanostructures for applications in nanodevices.     

Evolution of nanoparticles in gold-implanted glass

The interest in metal nanocrystals is focused on their nonlinear optical properties, as they are expected to have a large third-order nonlinear susceptibility. In order to explore the possibility of tuning the size and shape of metal nanocrystals, we implanted gold into fused silica substrate. The implantation energy was 1.1 MeV and doses were of 1, 3, and 6×10¹⁶ ions/cm². All samples were subsequently annealed in air at 1000 and 1100 °C. Grazing incidence small-angle X-ray scattering was used to study the morphology and the distribution of gold nanoparticles formed in the substrate. The clustering process is evident already during the implantation itself. Upon annealing, the number of clusters, as well as their size is increased. The clusters are smaller in the vicinity of the surface, where the effective implant concentration is lower, regardless of the annealing temperature. At the highest annealing temperature the clustering diverges into two distinct size distributions.     

Self-powered photoelectrochemical biosensing platform based on Au NPs@ZnO nanorods array

Photoanodes, which are used in photoelectrochemical (PEC) water splitting, have been shown to be applicable in the construction of a PEC biosensing platform. This was realized by replacing water oxidization with oxidation of an appropriate test molecule. Here, we have demonstrated the feasibility of adopting photoanodes consisting of zinc oxide nanorods arrays decorated with plasmonic gold nanoparticles (Au NPs@ZnO NRs) for the self-powered PEC bioanalysis of glutathione (GSH) in phosphate-buffered saline (PBS) at an applied bias potential of 0 V vs. Ag/AgCl. This heterostructure exhibited enhanced PEC properties because of the introduction of the Au/ZnO interface. Under visible light illumination, hot electrons from surface-plasmon resonance (SPR) at the Au NP surface were injected into the adjacent ZnO and subsequently driven to the photocathode. Under ultraviolet (UV) light illumination, the photogenerated electrons in ZnO tended to transfer to the fluorine-doped tin oxide due to the step-wise energy band structure and the upward energy band bending at the ZnO/ electrolyte interface. These results indicate that plasmonic metal/semiconductor heterostructure photoanodes have great potential for self-powered PEC bioanalysis applications and extended field of other photovoltaic beacons.

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