Tuning band structures of dyes for dye-sensitized solar cells : effect of different pi-bridges on the performance of cells

• Three organic dyes (LJ101, LJ102, and LJ103) with different pi-bridges such as thiophene, 3-hexylthiophene and 3, 4-ethyldioxythiophene, were prepared and applied for the dye-sensitized solar cells (DSSCs). The effect of the different pi-bridges on the photovoltaic performance of DSSCs were studied with the aid of quantum chemical calculation and electrochemical-impedance spectroscopy (EIS). The introduction of pi-bridges to construct dyes makes the absorption spectra red shift and enhances the molar extinction coefficient compared to the parent structure of TH305 without pi-conjugated bridge. However, the increasing conjugation length of the molecules decreases the performance of DSSCs, due to the two reduced gaps: one is between the LUMO levels of dyes and the conduction band edge of TiO2, the other one is the energy gap between the HOMO levels of dyes and the redox potential of iodide/triiodide. The conversion efficiencies of DSSCs based on LJ series dyes ranged from 6.1 to 6.4%, which are lower than that of TH305 (7.5%).

Subject headings

NATURVETENSKAP  -- Kemi (hsv//swe)

NATURAL SCIENCES  -- Chemical Sciences (hsv//eng)

Keyword

Conduction band edge

Conjugated bridges

Conjugation length

Dye-Sensitized solar cell

Dye-sensitized solar cells

Molar extinction coefficient

Photovoltaic performance

Quantum chemical calculations

Publication and Content Type

ref (subject category)

art (subject category)