Photoelectric characteristics of natural pigments self-assembly fabricated on TiO2/FTO substrate.

Natural pigment can act as an inexpensive and biologically-friendly dye, which is fabricated on a TiO2/FTO substrate. Natural pigments promote the efficiency of the photoelectric conversion in water-based DSSC with the aqueous electrolyte of the Ce+4/+3 system. The open-circuit voltage (Voc) of natural pigment in water-based DSSC is 0.640 V. The short-circuit current (Isc) of natural pigment in water-based DSSC is 0.658 mA/cm2. The efficiency of the photoelectric conversion in water-based DSSC of natural pigment is up to 0.131%. The natural pigments in DSSC are potentially applicable to turning solar energy into environmentally-friendly energy.

Ellipsometric studies of optical properties of local surface plasmon resonance for Au nanoparticles on the substrate.

Few ellipsometric studies have been conducted on Au self-assembled monolayers (SAM), with large discrepancies obtained for refractive index values. Because the Au NPs layer is a kind of composite layer, Au NPs and void, the effective media approximate (EMA) model was employed to investigate the optical properties of Au NPs. The reflective coefficient (approximately 1.2) was smaller than the extinction coefficient (approximately 2.5), which is different from the previous reports and corresponds to the Drude model. The absorption peak of surface plasmon resonance for Au NPs on the glass substrate was shifted from 580 nm to 480 nm.

Ellipsometric advances for local surface plasmon resonance to determine chitosan adsorption on layer-by-layer gold nanoparticles.

The ellipsometric measurement of local surface plasmon resonance (LSPR) caused by the adsorption of chitosan on layer-by-layer gold nanoparticles (Au NPs) was investigated. Six nanometer (6 nm) Au NPs were prepared and layer-by-layer Au NPs were fabricated to shift the LSPR to 520, 540, and 560 nm, respectively, due to the Mie theory. The thicknesses and the fractions of the layer-by-layer Au NPs were measured accurately using a combination of the Fresnel equation and the Maxwell-Garnett equations for ellipsometry. Furthermore, the position of the LSPR was shifted by chitosan. Using trajectory to record the trace of polarized light for ellipsometry resulting from LSPR, it was found that LSPR is predominantly induced when the LSPR position is close to the wavelength of the ellipsometric measurement. The trajectory circle of LSPR is very large for an increase of chitosan adsorption on Au NPs when the LSPR position is close to the detected wavelength. The linear approximation aspect quantifying the trajectory corresponds with the change of LSPR for the adsorption of chitosan, except for cases with low incidence and Brewster angles. The aspects and technologies of ellipsometry will benefit from the findings in this study, with potential applications in the fields of determination of molecular adsorption.