New Family of Ruthenium‐Dye‐ Sensitized Nanocrystalline TiO₂ Solar Cells with a High Solar‐Energy‐Conversion Efficiency

Abstract

A new type of ruthenium complexes 6–8 with tridentate bipyridine–pyrazolate ancillary ligands has been synthesized in an attempt to elongate the π‐conjugated system as well as to increase the optical extinction coefficient, possible dye uptake on TiO2, and photostability. Structural characterization, photophysical studies, and corresponding theoretical approaches have been made to ensure their fundamental basis. As for dye‐sensitized solar cell applications, it was found that 6–8 possess a larger dye uptake of 2.4 × 10–7 mol cm–2, 1.5 × 10–7 mol cm–2, and 1.3 × 10–7 mol cm–2, respectively, on TiO2 than that of the commercial N3 dye (1.1 × 10–7 mol cm–2). Compound 8 works as a highly efficient photosensitizer for the dye‐sensitized nanocrystalline TiO2 solar cell, producing a 5.65 % solar‐light‐to‐electricity conversion efficiency (compare with 6.01 % for N3 in this study), a short‐circuit current density of 15.6 mA cm–2, an open‐circuit photovoltage of 0.64 V, and a fill factor of 0.57 under standard AM 1.5 irradiation (100 mW cm–2). These, in combination with its superior thermal and light‐soaking stability, lead to the conclusion that the concomitant tridentate binding properties offered by the bipyridine‐pyrazolate ligand render a more stable complexation, such that extended life spans of DSSCs may be expected.

A New Ruthenium Sensitizer Containing Benzo[1,9]quinolizino(acridin-2-yl)vinyl-2,2′-bipyridine Ligand for Effective Nanocrystalline Dye-Sensitized Solar Cells

“…Adsorption of JJ-12 onto a TiO 2 electrode was observed to broaden the absorption band and to red shift the absorption threshold up to 770 nm, ensuring a good light-harvesting efficiency (Figure 2(b)). Such broadening and red shift have been observed in many ruthenium sensitizers on TiO 2 electrodes [25,26]. We also observed that the JJ-12 exhibited strong luminescence maxima at 740-755 nm when they were excited with their MLCT absorption bands at 298 K in an air-equilibrated ethanol solution.…”

PtII Complexes with 6‐(5‐Trifluoromethyl‐Pyrazol‐3‐yl)‐2,2′‐Bipyridine Terdentate Chelating Ligands: Synthesis, Characterization, and Luminescent Properties

“…[21] The central Pt À N distance of the ligand fpbpy is shorter than those of the outer nitrogen atoms, mainly because of the steric demand as documented in the literature. [18] The Pt À Cl(1) distance of 2.314(3) is comparable to that of the other Pt II -chloride complexes. [22] Furthermore, complex 1 exhibited a head-to-tail stacking along the b axis of the crystal lattice, giving a zigzag [Pt] n metal chain with intermolecular Pt···Pt distances of 3.385 and a PtÀPtÀPt angle of 153.598.…”

“…The required terdentate chelate fpbpyH was obtained by a Claisen condensation reaction employing 6-acetyl-2,2'-bipyridine and ethyl trifluoroacetate, followed by treatment with an excess of hydrazine hydrate in refluxing ethanol according to procedures reported in the literature. [16,18] This ligand has a high potential for forming the anionic tridentate chelate by facile deprotonation during the reaction with a transition-metal reagent in basic media.…”

Synthesis, Characterization, and Biological Evaluation of New Ru(II) Polypyridyl Photosensitizers for Photodynamic Therapy

“…45,46 It has been shown that Ru(II) polypyridyl complexes perform very efficiently in DSSCs. [47][48][49][50][51][52][53] The complexes used for DSSCs exhibit interesting photophysical properties, such as light absorption across the visible spectrum and long excited-state lifetimes. [54][55][56][57] These properties make this class of complexes highly interesting as potential PS in PDT.…”