RESUMO
We report the synthesis, characterization, and photovoltaic properties of four ruthenium complexes (CI101, CBTR, CB111, and CB108) having various N-heterocyclic carbene ancillary ligands, pyridine-imidazole, -benzimidazole, -dithienobenzimidazole, and -phenanthroimidazole, respectively. These complexes were designed to investigate the effect of extended conjugation ordained from ring fusion on the power conversion efficiencies of the solar cells. The device sensitized by CB108, the pyridine-phenanthroimidazole conjugated complex, showed an improved efficiency (9.89%) compared to those of pyridine-benzimidazole conjugated system (CBTR, 9.72%) and the parent unfused ring system (CI101, 6.24%). Surprisingly, the sulfur-incorporated pyridine-dithienobenzimidazole system (CB111, 9.24%) exhibited a little lower efficiency than that of N719 (9.41%). The enhanced photovoltaic performance of CB108 was mainly attributed to the increase in electron lifetime and diffusion length confirmed by the electrochemical impedance spectroscopy.
RESUMO
The surface modification of the TiO2 photoelectrode film is one of the promising ways to improve the photovoltaic performance of dye-sensitized solar cell (DSSC). In this work for the acid treatment of TiO2 powder, fluorine containing compounds such as trifluoroacetic acid was carried out to enhance the properties of photoanode. In order to investigate the effect of trifluoroacetyl group, the TiO2 nanopowders were also treated with different acids such as acetic acid, nitric acid, hydrochloric acid, and sulfuric acid and their properties were compared. The TiO2 powders treated with both acetic acid and TFA have possessed smooth surface morphologies as well as enhanced particle dispersions with reduced particle sizes. Photoelectrodes prepared for these two kinds of TiO2 powders accommodated high amounts of dye loading and exhibited excellent light transmittance (wavelength region of 400600 nm). Electrochemical impedance spectroscopy analysis showed the smallest radius of the semicircle which indicates the enhanced rate of electron transport for the cell based photoelectrode with trifluoroacetic acid treated TiO2 powder. The solar cell from the untreated TiO2 film showed the power conversion efficiency of 8.86% and the highest efficiency of 9.51% was achieved by the cell fabricated from trifluoroacetic acid treated TiO2 film.
RESUMO
New heteroleptic Ru(ii) complexes consisting of pyridylimine as an ancillary ligand were synthesized and characterized for applications in dye sensitized solar cells. Complexes with cis and trans configurations around the central ruthenium metal were obtained using simple synthetic protocols by varying the substituents on the pyridylimine ligands. The geometries of these complexes were confirmed by single crystal X-ray analysis. The effect of the difference in the configurations of these complexes on their device performances was studied and the sensitizer with a trans arrangement around the metal showed a higher overall conversion efficiency (η) of 7.27% than that of the cis configured complex (η = 2.04%).
RESUMO
Novel organic pyridinium ylide sensitizers (NO109-111) consisting of various anchoring groups were synthesized and characterized for applications in dye sensitized solar cells. Compared with the pyridine-N-oxide dye (NO108), the ylide sensitizers with strong electron-withdrawing acceptors exhibited dominant ultraviolet absorption properties and efficient binding abilities to the TiO2 surface. Among these dyes, the pyridinium ylide NO111 sensitized solar cell showed the highest efficiency (5.15%), which was improved to 7.41% by employing coadsorbent chenodeoxycholic acid.