A Cu complex featuring a hexadentate ligand was synthesized and evaluated as a redox shuttle in dye-sensitized solar cell (DSC) devices, which exhibited excellent performance under low-light conditions. Cu-based redox shuttles (RSs) have been shown to perform remarkably well under low-light conditions; however, most of the known Cu-based RSs employ bidentate pyridyl ligands and often require bulky flanking groups adjacent to the nitrogen donors of these ligands to prevent distortion and binding of exogenous Lewis bases such as 4-tert-butylpyridine (TBP) that are added to enhance cell performance. Without the bulky substituents, the bidentate ligands are susceptible to ligand exchange with TBP. In this context, we have developed a Cu-based RS with a preorganized multidentate ligand designed to facilitate efficient electron transfer kinetics and high stability via the chelate effect. The Cu system, [Cu­(bpyPY4)]2+/+, reported here is supported by the hexadentate polypyridyl ligand bpyPY4 (6,6′-bis­(1,1-di­(pyridine-2-yl)­ethyl)-2,2′-bipyridine) and examined as a RS in DSCs. From X-ray crystallography and variable-temperature 1H NMR studies, bpyPY4 provides a dynamic coordination environment around the metal center. Cyclic voltammetry and UV–visible and NMR spectroscopy indicate that noncoordinated pyridyl donors block binding of TBP to copper. DSC devices using [Cu­(bpyPY4)]2+/+ as the redox electrolyte gave a power conversion efficiency (PCE) value of 4.9% under 1 sun illumination (100 mW/cm2). Strikingly, the device performance increased to 11.11% when irradiated with 2400 lux (0.5 mW/cm2) via a fluorescent lamp light source and improved further to 15.2% PCE at 13500 lux (2.10 mW/cm2). The Cu redox shuttle is an intriguing candidate for implementation with narrow band gap sensitizers with low oxidation potentials, which are important for high photocurrent DSC devices.

Although range scanning technology has offered great improvements to digital model creation in recent years, it has also introduced some new concerns. Specifically, recent work shows that topological errors such as tiny handles can significantly lower the overall quality of range-scanned models for down-stream applications (such as simplification and parameterization). In this paper we present our investigation into the source of this topological error in the range scanning process, and our methods to alleviate the error. We concentrated our investigation of the scanning process on: (1) signal noise or calibration error in the laser scanner (resulting in bad data points) and (2) error during the model reconstruction phase. We found that by modifying the surface reconstruction phase of the range scanning process, we were able to reduce the amount of topological noise in the resulting 3D model by up to 60 percent.

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