Study on benzoic acid by THz time-domain spectroscopy and density functional theory

Density functional theory (DFT) and time-dependent density functional theory (TDDFT) calculations were carried out to study the ground state geometries, electronic structures, and absorption spectra of 4-(cyanomethyl)benzoic acid based dyes (AG1 and AG2) used for dye-sensitized solar cells (DSSCs). The excited states properties and the thermodynamical parameters of electron injection were studied. The results showed that (a) two dyes have uncoplanar structures along the donor unit and conjugated bridge space, (b) two sensitizers exhibited intense absorption in the UV-Vis region, and (c) the excited state oxidation potential was higher than the conduction band edge of TiO2photoanode. As a result, a solar cell based on the 4-(cyanomethyl)benzoic acid based dyes exhibited well photovoltaic performance. Furthermore, nine dyes were designed on the basis of AG1 and AG2 to improve optical response and electron injection.

Download Full-text

Synthesis of a New Photochromic ZrO2 Precursor for Preparation of Functional Thin Films

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.320.175 ◽

2006 ◽

Vol 320 ◽

pp. 175-178 ◽

Cited By ~ 5

Author(s):

Kaori Nishizawa ◽

Haruhiko Fukaya ◽

Takeshi Miki ◽

Kazuyuki Suzuki ◽

Kazumi Kato

Keyword(s):

Density Functional Theory ◽

Benzoic Acid ◽

Uv Irradiation ◽

Density Functional ◽

Room Temperature ◽

Dft Calculation ◽

Precursor Solution ◽

Peak Position ◽

Functional Theory ◽

The Difference

A new photochromic ZrO2 precursor solution was prepared using zirconium tetra-n-butoxide, 4-(phenylazo)benzoic acid and ethyleneglycol monomethylether. The ZrO2 precursor solution was irradiated with ultraviolet light (UV) at room temperature. After that, UV-irradiated precursor solution was irradiated with visible light (Vis) at room temperature. UV-Vis spectra were measured before irradiation, after UV irradiation and Vis irradiation. Changes of UV-Vis spectra indicated that the new ZrO2 precursor including 4-(phenylazo)benzoic acid shows photochromism. The phenomena have synchronized with reversible photoisomerization of 4-(phenylazo)benzoic acid in the precursor. In addition, the difference of peak position originated from Zr-O CT transition between before UV irradiation and after UV irradiation increased with increasing the concentration of 4-(phenylazo)benzoic acid. Furthermore, the optimized structure of the new ZrO2 precursor was derived by density functional theory (DFT) calculation.

Download Full-text

Study on the Terahertz Time Domain Spectrum of P-Chloroaniline

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.441.741 ◽

2012 ◽

Vol 441 ◽

pp. 741-745

Author(s):

Si Chen ◽

Chao Yan ◽

Bin Luo ◽

Bin Yang

Keyword(s):

Density Functional Theory ◽

Hydrogen Bonding ◽

Time Domain ◽

Azo Dye ◽

Density Functional ◽

Phonon Mode ◽

Terahertz Time Domain Spectroscopy ◽

Functional Theory ◽

Bonding Force ◽

The Density Functional Theory

P-chloroaniline is one of the most important azo dye intermediates. It is a highly desired research on the identification of P-chloroaniline. Terahertz time domain spectroscopy (THz-TDS) is sensitive to the molecule structure of compound. In this paper, the spectra of P-chloroaniline located at the region from 0.1 to 3 THz were tested by THz-TDS system, and then the geometry structure of p-chloroaniline at the range of 0 THz to 10 THz was optimized, resonance frequency was calculated by Gussian03 software based on the density functional theory (DFT). The results showed that the absorbance peaks at 1.96 THz and 2.20 THz were caused by the hydrogen bonding force or crystal phonon mode, and suggested that it is feasible to identify P-chloroaniline by THz-TDS, which is of great value to the examination of banned azo dyes in the future.

Download Full-text