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In this paper, we demonstrated a roughness dependent chemical vapor deposition (CVD) process to selectively grow aligned carbon nanotube bundles on silicon substrates with microscratches. Our results show that the aligned nanotubes of uniform length (around 2 μm) and diameter (20~30 nm) are assembled to nanotube bundles and in-plane vertically aligned with the microscratches. The microscratch-selective nanotube growth offers a promising approach for the fabrication of 3-D nanotube architectures in a single CVD process. [ABSTRACT FROM AUTHOR]

Quasi-solid-state dye-sensitized solar cells were fabricated using a high molecular polymer redox electrolyte. Poly(ethylene oxide) (PEO) and Poly(vinylidenefluoride-co-hexafluoropropylene) (P(VDF-HFP)) were used to form a stable quasi-solid structure and a three-dimensional gel polymer network structure. The polymer electrolytes were composed of LiI, I2, and DMPII in the mixture of propylene carbonate (PC) and γ-butyrolactone (GBL) with different volume ratios. A metal-free organic dye (indoline dye D102) was used as a sensitizer. The ionic conductivity of the gel polymer electrolytes was measured with Electrochemical Impedance Spectroscopy (EIS). The dependence of the ionic conductivity on the volume ratio of PC to GBL was investigated. The volume ratio of the mix solvent, weight ratio of PEO/P(VDF-HFP), and the weight ratio of TiO2 fillers were optimized. The optimized quasi-solid-state cell exhibited an efficiency of 5.49% at full sunlight (air mass 1.5, 60 mW/cm2) irradiation. [ABSTRACT FROM AUTHOR]

Thermosetting polymer gel electrolytes (TPGEs) based on poly(acrylic acid)-poly(ethylene glycol) (PAA-PEG) hybrid were prepared and applied to fabricate dye-sensitized solar cells (DSCs). N-methylpyrrolidone (NMP) and γ-butyrolactone (GBL) were used as solvents for liquid electrolytes and LiI and KI as iodide source, separately. The microstructure of PAA-PEG shows a well swelling ability in liquid electrolyte and excellent stability of the swollen hybrid. The TPGE was optimized in terms of the liquid electrolyte absorbency and ionic conductivity photovoltaic performance. Quasi-solid-state DSCs containing TPGE with optimized KI electrolyte show higher efficiency, voltage, fill factor, and lower photocurrent than those with LiI electrolyte. The related mechanism was discussed. A quasi-solid-state DSC fabricated with optimized polymer gel electrolyte obtained an overall energy conversion efficiency of 4.90% under irradiation of 100 mW/cm2 (AM1.5). [ABSTRACT FROM AUTHOR]

The titanium dioxide nanotubes (TiNTs) were directly prepared from commercial P25 TiO2 powder via alkali hydrothermal transformation. The fabricated nanotubes had an average outer diameter of 8-10 nm and the inner diameter of 4-6 nm with several hundred nanometers in length. The prepared nanotubes were added into TiO2 nanoporous electrodes for the fabrication of dye-sensitized solar cells (DSCs). The photoelectrochemical characteristics and dye-adsorption properties were investigated by varying the proportion of the nanotubes incorporated into TiO2 working electrodes. The electron transport resistance, electron life time, and dye adsorption properties were evaluated in terms of electrochemical impedance spectra and photovoltaic characteristics of the solar cells. Compared to DSCs based on TiO2 nanoparticles, the fill factor, open-voltage, and photocurrent based on TiNT/P25 hybrid increased significantly. High conversion efficiency of light-to-electricity of 7.41% under illumination of simulated AM 1.5 sunlight (100 mW/cm2) was achieved for DSCs using optimized proportions of TiO2 nanotubes incorporated into TiO2 electrodes. The studies provided a promising method for the development of high efficiency and low cost DSCs. [ABSTRACT FROM AUTHOR]