Search

New isomeric sensitizers containing an imine–carbene (IC)-based ancillary ligand, isomers IC101 and IC102, were designed for application in dye-sensitized solar cells (DSSCs). These ruthenium complexes were synthesized and isolated using simple purification methods. The DSSCs sensitized with IC101 and IC102 exhibited overall conversion efficiencies of 6.32% and 6.59%, respectively. Although these two isomers gave similar device output, reduction in the power conversion efficiency (5.52%) was observed when the cell was fabricated using a 1 : 1 mixture of both sensitizers. The results highlight the importance of isomeric purity of the sensitizing complexes to gain high performance DSSCs. [ABSTRACT FROM AUTHOR]

Ruthenium metal complexes consisting of various functionalized carbene-pyridyl anchoring ligands were synthesized, characterized, and tested for their power conversion capabilities. Carboxylate (DC101), hydroxamate (DC107), and acyl azide (DC108) groups were explored as anchors to identify a suitable and efficient binding functionality for the unique characteristic carbene-pyridyl ligand. The hydroxamate anchoring group was shown to be the most efficient anchoring group for the carbene-pyridyl ligand and the device based on dye DC107 exhibited the best efficiency (η) of 4.97% compared to those of the other prepared sensitizers. Electrochemical impedance spectroscopy studies on the devices based on these dyes justified their performances. This is the first case of an investigation utilizing σ electron donating carbene-pyridine as the anchoring ligand and it was found to be more suitable for use as an ancillary group. [ABSTRACT FROM AUTHOR]

A new type of carbene-based ruthenium sensitizer, CB104, with a highly conjugated ancillary ligand, diphenylvinylthiophene-substituted benzimidazolepyridine, was designed and developed for dye-sensitized solar cell applications. The influence of the thiophene antenna on the performance of the cell anchored with CB104 was investigated. Compared with the dye CBTR, the conjugated thiophene in the ancillary ligand of CB104 enhanced the molar extinction coefficient of the intraligand π-π* transition and the intensity of the lower energy metal-to-ligand charge-transfer band. However, the incident photon-to-current conversion efficiency spectrum of the cell anchored with CB104 (0.15 m M) showed a maximum of 63 % at 420 nm. The cell sensitized with the dye CB104 attained a power conversion efficiency of 7.30 %, which was lower than that of the cell with nonconjugated sensitizer CBTR (8.92 %) under the same fabrication conditions. The variation in the performance of these two dyes demonstrated that elongating the conjugated light-harvesting antenna resulted in the reduction of short-circuit photocurrent density, which might have been due to the aggregation of dye molecules. In the presence of a coabsorbate, chenodeoxycholic acid, the CB104-sensitized cell exhibited an enhanced photocurrent density and achieved a photovoltaic efficiency of 8.36 %. [ABSTRACT FROM AUTHOR]

A new series of N-heterocyclic carbene (NHC)-pyridine ruthenium complexes incorporating a carbene unit as an ancillary ligand were designed and successfully synthesized by using simple synthetic methods. The photophysical, electrochemical and photovoltaic properties of these NHC-pyridine based ruthenium complexes were investigated. These complexes showed photoelectric conversion efficiencies in the range of 6.43 ∼ 7.24% under the illumination of AM 1.5 (100 mW cm−2). Interestingly, the modifications on the ancillary ligand of these sensitizers by removal of an alkoxyl group and replacement of the octyl chain with a 3,5-difluorobenzyl group showed a 13% increase in the conversion efficiency for the CifPR dye. These results demonstrated that structural modifications on the NHC-pyridine ancillary ligand of ruthenium complexes results in dye-sensitized solar cells exhibiting a comparable cell performance to that obtained using the standard N719 dye. [ABSTRACT FROM AUTHOR]