Energy-Level and Molecular Engineering of Organic D-π-A Sensitizers in Dye-Sensitized Solar Cells

Abstract

A series of organic D-π-A sensitizers composed of different triarylamine donors in conjugation with the thienothiophene unit and cyanoacrylic acid as an acceptor has been synthesized at a moderate yield. Through tuning the number of methoxy substituents on the triphenylamine donor, we have gradually red-shifted the absorption of sensitizers to enhance device efficiencies. Further molecular engineering by the substitution of two hexyloxy chains in place of the methoxy groups allows fabricating a solvent-free dye-sensitized solar cell with a power conversion efficiency of 7.05% measured under the air mass 1.5 global sunlight. Time-and frequency-domain photoelectrical techniques have been employed to scrutinize the aliphatic chain effects with a close inspection on effective electron lifetime, diffusion coefficient, and diffusion length.

Solvent‐Free Ionic Liquid Electrolytes for Mesoscopic Dye‐Sensitized Solar Cells

“…It is interesting to see a red shift of the absorption peaks along with the introduction of stronger electron-donating alkoxy groups to the donor part of these D-p-A dyes (C207, C202, and C208). [16] An increased red spectral response is noticed from C202 to C208. This, however, is offset by a decrease in the molar extinction coefficient, which can be understood by a low oscillator strength of the charge-transfer transition due to reduced electronic coupling.…”

“…A $7% cell with the amphiphilic C206 sensitizer shows an excellent stability measured under light soaking at 60 8C. [16] In an attempt to shift the spectral response further and to reduce the solubility of organic sensitizers in the electrolytes, the p character of spacer was extended from thienothiophene to dithienithiophene. The molecular structure of these sensitizers is shown in Figure 5 and their electronic absorption and emission spectral values are given in Table 1.…”

Mapping the frontier electronic structures of triphenylamine based organic dyes at TiO2interfaces

“…[4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19] Specifically the organic sensitizers compete with the more traditional dyes in the thin solid solar cells where high extinction coefficients of the dyes are needed for efficient light harvesting. The relatively easy synthetic routes of organic dye makes them easy to modify with respect to position of the energy levels important for the DSC energy conversion.…”

Fused-Thiophene Based Materials for Organic Photovoltaics and Dye-Sensitized Solar Cells

“…Wang et al reported a series of organic dyes (15)(16)(17)(18) that contain a triphenylamine unit as the donor and cyanoacetic acid as the acceptor [37]. These sensitizers were prepared with different alkyl chains on the triphenylamine unit to tune their HOMO energy levels.…”