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We prepared the ionic dyes and investigated their electrochemical properties and photosensitizing performances in the quasi-solid state dye-sensitized solar cells (QS-DSSCs). The LUMO energy level of ionic dye with carbazole moiety is higher than that of the dyes with phenothiazine and triphenylamine chromophore, resulting in highest power conversion efficiency (PCE) in the QD-DSSC. Compared with Ru-complex sensitizer, the ionic dyes showed relatively low photovoltaic performance in the QS-DSSCs, originating in lower LUMO energy level. The effect of Li+ion in the quasi-solid state electrolyte on the photovoltaic characteristics of QS-DSSCs was investigated in order to confirm the correlation between the conduction band of TiO2electrode and LUMO energy level of photosensitizers. The conduction band of TiO2electrode could be reduced by adding the Li+ion in the electrolyte, attributing for the enlargement of PCE value in the QS-DSSC.

We prepared novel organic photo-sensitizers based on a carbazole framework containing various acceptors with thiophene bridge units in the chromophore for the application to dye-sensitized solar cell (DSSC). Furthermore, organic dyes without bridge in the chromophore also synthesized to investigate the correlation between conjugation lengths and photon-to-current efficiency (PCE). Compared to non-bridged dyes, the DSSCs device containing multi-anchoring dyes with thiophene bridge exhibited much higher PCEs, resulting from efficient electron extraction pathways, higher molar extinction coefficients, and better light absorption in longer wavelengths.

Organic dyes containing multi-acceptors/anchors in a chromophore were synthesized for use in a dye-sensitized solar cell. The photovoltaic properties of organic dyes composed of different acceptor in their chromophores were measured to identify the effects on the DSSC performance. The organic dye, 4 containing multi-cyanoacrylic acid as the electron acceptor showed a power conversion efficiency of 4.7% under AM 1.5 illumination (100 mW cm−2) in an photo active area of 0.24 cm2, short circuit current density of 12.9 mA cm−2, open circuit photo voltage of 0.62 V and a fill-factor of 60%. The retarded recombination kinetics from TiO2 electrode to electrolyte enhanced the electron life time of organic dye, 4 in the photoanode in DSSC that was well confirmed with the impedance analysis.