Triarylamine-functionalized ruthenium dyes for efficient dye-sensitized solar cells

Improvements in photoelectric performance of dye-sensitised solar cells using ionic liquid-modified TiO2 electrodes

One of the major problems in dye-sensitised solar cells (DSSCs) is the aggregation of dyes on TiO₂ electrodes, which leads to undesirable electron transfer. Various anti-aggregation agents, such as deoxycholic acid, have been proposed and applied to prevent dye aggregation on the electrodes. In this study, we designed and synthesised a phosphonium-type ionic liquid that can be modified on the TiO₂ electrode surface and used as a new anti-aggregation agent. Although the modification of the ionic liquid onto the electrode reduced the amount of dye adsorbed on the electrode, it showed a significant anti-aggregation effect, thereby improving the photovoltaic performance of DSSCs with N3 and J13 dyes. This finding suggests that ionic liquids are effective as anti-aggregation agents for DSSCs.

The modification of the phosphonium-type ionic liquid onto the TiO₂ electrode reduced the amount of dye adsorbed on the electrode and showed significant aggregation effect, thereby improving the photovoltaic performance of DSSCs.

Superior Light-Harvesting Heteroleptic Ruthenium(II) Complexes with Electron-Donating Antennas for High Performance Dye-Sensitized Solar Cells

Three heteroleptic polypyridyl ruthenium complexes, RC-41, RC-42, and RC-43, with efficient electron-donating antennas in the ancillary ligands were designed, synthesized, and characterized as sensitizers for dye-sensitized solar cell. All the RC dye sensitizers showed remarkable light-harvesting capacity and broadened absorption range. Significantly, RC-43 obtained the lower energy metal-ligand charge transfer (MLCT) band peaked at 557 nm with a high molar extinction coefficient of 27 400 M(-1) cm(-1). In conjunction with TiO2 photoanode of submicrospheres and iodide-based electrolytes, the DSSCs sensitizing with the RC sensitizers, achieved impressively high short-circuit current density (19.04 mA cm(-2) for RC-41, 19.83 mA cm(-2) for RC-42, and 20.21 mA cm(-2) for RC-43) and power conversion efficiency (10.07% for RC-41, 10.52% for RC-42, and 10.78% for RC-43). The superior performances of RC dye sensitizers were attributed to the enhanced light-harvesting capacity and incident-photon-to-current efficiency (IPCE) caused by the introduction of electron-donating antennas in the ancillary ligands. The interfacial charge recombination/regeneration kinetics and electron lifetime were further evaluated by the electrochemical impedance spectroscopy (EIS) and transient absorption spectroscopy (TAS). These data decisively revealed the dependences on the photovoltaic performance of ruthenium sensitizers incorporating electron-donating antennas.

Influence of Ancillary Ligands in Dye-Sensitized Solar Cells

Dye-sensitized solar cells (DSSCs) have motivated many researchers to develop various sensitizers with tailored properties involving anchoring and ancillary ligands. Ancillary ligands carry favorable light-harvesting abilities and are therefore crucial in determining the overall power conversion efficiencies. The use of ancillary ligands having aliphatic chains and/or π-extended aromatic units decreases charge recombination and permits the collection of a large fraction of sunlight. This review aims to provide insight into the relationship between ancillary ligand structure and DSSC properties, which can further guide the function-oriented design and synthesis of different sensitizers for DSSCs. This review outlines how the new and rapidly expanding class of chelating ancillary ligands bearing 2,2'-bipyridyl, 1,10-phenanthroline, carbene, dipyridylamine, pyridyl-benzimidazole, pyridyl-azolate, and other aromatic ligands provides a conduit for potentially enhancing the performance and stability of DSSCs. Finally, these classes of Ru polypyridyl complexes have gained increasing interest for feasible large-scale commercialization of DSSCs due to their more favorable light-harvesting abilities and long-term thermal and chemical stabilities compared with other conventional sensitizers. Therefore, the main idea is to inspire readers to explore new avenues in the design of new sensitizers for DSSCs based on different ancillary ligands.

Regulating ancillary ligands of Ru(ii) complexes with square-planar quadridentate ligands for more efficient sensitizers in dye-sensitized solar cells: insights from theoretical investigations

Modification of ancillary ligands of Ru(ii) complexes with square-planar quadridentate ligands presents an efficient strategy to tune the performance of DSSCs.