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A state-of-the-art review highlighting the theory, role and the materials of the scattering layer in dye-sensitized solar cells.

One of the major problems that humanity has to face in the next 50 years is the energy crisis. The rising population, rapidly changing life styles of people, heavy industrialization and changing landscape of cities have increased energy demands, enormously. The present annual worldwide electricity consumption is 12 TW and is expected to become 24 TW by 2050, leaving a challenging deficit of 12 TW. The present energy scenario of using fossil fuels to meet the energy demand is unable to meet the increase in demand effectively, as these fossil fuel resources are non-renewable and limited. Also, they cause significant environmental hazards, like global warming and the associated climatic issues. Hence, there is an urgent necessity to adopt renewable sources of energy, which are eco-friendly and not extinguishable. Of the various renewable sources available, such as wind, tidal, geothermal, biomass, solar, etc., solar serves as the most dependable option. Solar energy is freely and abundantly available. Once installed, the maintenance cost is very low. It is eco-friendly, safely fitting into our society without any disturbance. Producing electricity from the Sun requires the installation of solar panels, which incurs a huge initial cost and requires large areas of lands for installation. This is where nanotechnology comes into the picture and serves the purpose of increasing the efficiency to higher levels, thus bringing down the overall cost for energy production. Also, emerging low-cost solar cell technologies, e.g. thin film technologies and dye-sensitized solar cells (DSCs) help to replace the use of silicon, which is expensive. Again, nanotechnological implications can be applied in these solar cells, to achieve higher efficiencies. This paper vividly deals with the various available solar cells, choosing DSCs as the most appropriate ones. The nanotechnological implications which help to improve their performance are dealt with, in detail. Additionally, the economic and ecological aspects of using nanotechnology are briefly introduced.

We have synthesized 3-D flower-like mesostructured TiO2 from one-dimensional electrospun TiO2–SiO2 nanocomposites through a modified titanate route for dye-sensitized solar cell (DSC) application. The TiO2 3-D mesoflowers with commendable internal surface area, crystallinity, and a good light scattering property satisfy the prerequisites of a DSC photoanode material. The starting TiO2–SiO2 composite, intermediate titanate, and final 3-D mesoflowered TiO2 were characterized by spectroscopy, microscopy, and surface area measurements. A DSC employing 3-D mesoflowered TiO2 as the photoanode showed a power conversion efficiency of 8.3% which was 23% higher than that of commercial P-25 (6.37%).

This study evaluated the shear bond strength of zirconia bonded to dentin specimens using a self etch dual cure resin cement after various surface treatments of zirconia. Twenty zirconia rods (3 × 2.5 mm) were prepared from zirconia blocks and assigned into 5 groups for the following surface treatments. (1) Group I: Control (C) no treatment (2) Group II: airborne-particle abrasion (APA), (3) Group III: hydrofluoric acid etching (HF), (4) Group IV: hydrofluoric acid etching followed by silanation (HF/S), and (5) Group V: application of zirconia primer (Z). Dentin Specimens were prepared from extracted molars stored in 0.5% chloramine-T. Zirconia rods were bonded to dentin using resin cement (Multilink Speed), then light polymerized. The specimens tested for failure were tested using the notched shear bond test method in a universal loading apparatus. One way ANOVA followed by Tukey HSD for cell means were used to analyze the data (=0.05). The highest values were obtained with group V (Z) (8.66 MPa) followed by group II (APA) (6.71 MPa), and group IV (HF/S) (4.41 MPa). The least values were obtained for group III (HF) (3.88 MPa) with no significant difference (P value 0.53) between group III (HF) (3.88 MPa) and group I (C) (3.70 MPa). Among the surface treatments employed in this study zirconia primer application is a practical procedure to improved bond strength of zirconia to resin cement followed by Airborne Particle Abrasion with 50 μm Al2O3 particles.