A new synthetically facile heteroleptic ruthenium(II) sensitizer (NBu(4))[Ru(4,7-dpp)(dcbpyH)(NCS)(2)], coded as YS5, where NBu(4) is tetrabutylammonium, 4,7-dpp is 4,7-diphenyl-1,10-phenanthroline, and dcbpyH is the singly deprotonated surface anchoring derivative of 4,4'-dicarboxy-2,2'-bipyridine (dcbpyH(2)), was designed, synthesized, and incorporated into regenerative mesoscopic titania-based dye-sensitized solar cells. The sensitizer has characteristic broad, high extinction coefficient MLCT bands spanning the visible spectrum. The compound was fully characterized by 1D and 2D (1)H NMR, MALDI-TOF-MS, UV-vis, photoluminescence, Raman, IR, and electrochemistry. YS5 exhibits strong visible absorption properties with a molar extinction coefficient of 1.71 x 10(4) M(-1) cm(-1) at its 522 nm maximum. In operational liquid junction-based DSSCs under simulated AM 1.5G one-sun excitation (100 mW/cm(2)), the photovoltaic performance of YS5 compares almost equally against the current benchmark sensitizer N719 in side-by-side comparisons, producing a power conversion efficiency of 6.05% with a maximum IPCE of 65% at 540 nm. The data presented in this manuscript strongly suggest that YS5 is indeed a viable sensitizer for nanocrystalline TiO(2)-based DSSCs, seemingly poised for widespread adaptation.

High-quality compositionally tunable ternary PbSe(x)S(1-x) (x = 0.23, 0.39, 0.49, 0.68, and 0.90) nanowires (NWs) and their binary analogues have been grown using solution-liquid-solid growth with lead(II) diethyldithiocarbamate, Pb(S(2)CNEt(2))(2), and lead(II) imido(bis(selenodiisopropylphosphinate)), Pb((SeP(i)Pr(2))(2)N)(2), as single-source precursors. The alloyed nature of PbSe(x)S(1-x) wires was confirmed using ensemble X-ray diffraction and energy dispersive X-ray spectroscopy (EDXS). Single NW EDXS line scans taken along the length of individual wires show no compositional gradients. NW compositions were independently confirmed using inductively coupled plasma atomic emission spectroscopy. Slight stoichiometric deviations occur but never exceed 13.3% of the expected composition, based on the amount of introduced precursor. In all cases, resulting nanowires have been characterized using transmission electron microscopy. Mean diameters are between 9 and 15 nm with accompanying lengths that range from 4 to 10 μm. Associated selected area electron diffraction patterns indicate that the PbSe(x)S(1-x), PbSe, and PbS NWs all possess the same <002> growth direction, with diffraction patterns consistent with an underlying rock salt crystal structure.

This work focuses upon the effects of electrolyte composition, specifically the role of Li+ and I− ions, on the resultant photovoltaic performance of dye-sensitized solar cells (DSCs) based on a new Os(II) polypyridine complex of mixed denticity, [Os( t Bu3tpy)(dcbpyH2)(NCS)]PF6 (1). Photophysical and electrochemical characterization of 1 confirmed the suitability of this dye to serve as a sensitizer for regenerative DSCs on mesoscopic titania films. Device photovoltaic performances were assessed by measuring external quantum efficiencies as a function of wavelength, and current−voltage curves, the latter under simulated AM1.5G one-sun illumination. Varying the concentration of LiI in the redox electrolyte affects the short-circuit photocurrent (J SC), open-circuit voltage (V OC), fill factor (ff), power conversion efficiency (η), and external quantum efficiency (EQE) of the individual devices. Increasing the concentration of LiI results in enormous increases in J SC in the Os(II)-based devices accompanied by corresponding decreases in V OC. Independently increasing the concentration of I− by using either tetrabutylammonium iodide (TBAI) or the ionic liquid 1-n-propyl-3-methylimidazolium iodide (PMII) was found to increase J SC without concomitantly lowering the V OC. These observations are discussed and directly compared in parallel to devices based on the benchmark sensitizer N3, cis-Ru(dcbpyH2)2(NCS)2. The combined results suggest that the photovoltaic performance of Os(II)-based DSCs can indeed be optimized by simply modifying the composition of redox electrolytes used in the operational sandwich cells. An abundance of I− appears to be crucial for the effective regeneration of oxidized surface-bound osmium sensitizers and therefore for the production of higher photocurrents in these devices. We note that select devices based on 1 represent the record power conversion efficiency for an Os(II)-based DSC measured under simulated AM1.5G one-sun illumination, η = 4.7%.

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