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New-type silica Λ-shape wedge arrays (SWAs) were fabricated by a combined process of template fabrication, hot embossing and sol–gel replication. Using silica needle arrays (SNAs) as template, the configuration of Λ-shape was transferred from SNAs to PMMA/PC molds by hot-pressing process. Then they were casted to form silica Λ-shape wedge arrays by sol–gel process. Using this procedure, high quality silica Λ-shape wedge arrays can be obtained with designed sizes and shapes over a large area. The taper height and interspace of SWAs can be tuned by the imprint depth during the hot-embossing process. This technology provides a cost-effective method to fabricate Λ-shape silica wedges. By changing the primal template, other patterned silica substrate can also be fabricated, such as grating, pillar and spherical structures. These silica based microstructure can find many applications in semiconductor devices, solar cells and optics etc.

The positive effects of the vacuum assistant dye adsorption (VADA) process on the performances of the dye-sensitized solar cells (DSSCs) were investigated experimentally. Using commonly used materials and processes as a demonstration, nanoporous films and the resulted solar cells with different dye adsorption processes were fabricated and characterized for comparison. The amounts of dyes adsorbed by the TiO2 nanoporous films were found to be enhanced greatly compared with dyes adsorbed in ambient condition. In accordance, a relative increase of about 29% for the short-circuit currents (Isc) and 32% for the efficiencies (η) were observed for the resulted DSSCs. Photocurrent-voltage measurement indicated that the lifetime of the photogenerated charge carriers changed little. Hence, such improvements were originated from the application of VADA process, which realized full contact between the dye solution and TiO2 nanoparticles by driving away the air bubbles concealed in the nanoporous film. The VADA process may be also applied in other kinds of solar cells, such as solid state DSSCs and organic or flexible solar cells to enhance the dye adsorption and further increase their efficiencies.

Antireflective surfaces are often realized by minimizing the refractive index contrast between the air and substrate using subwavelength microstructures. In this paper, we introduce another kind of geometry-induced antireflective surface using multireflection to suppress reflection to a very low extent. This surface is composed of micro-∧-shape array with the wedge size much larger than the wavelength of the incident light. Simulation and experimental results show that the micro-∧-shape array can effectively suppress the reflection within wide incident angles and large wavelength ranges. The enhanced light adsorption caused by the greatly increased light path length within the micro-∧-shape array is responsible for the antireflection phenomena. Such antireflective surface may find various applications, in solar cells, for example.