We study the electrochemical, spectroscopic, and photocatalytic properties of a series of Ru(II)−Re(I) binuclear complexes linked by bridging ligands 1,3-bis(4′-methyl-[2,2′]bipyridinyl-4-yl)propan-2-ol (bpyC 3 bpy) and 4-methyl-4′-[1,10]phenanthroline- [5,6-d]imidazol-2-yl)bipyridine (mfibpy) and a tetranuclear complex in which three [Re(CO) 3 Cl] moieties are coordinated to the central Ru using the bpyC 3 bpy ligands. In the bpyC 3 bpy binuclear complexes, 4,4′-dimethyl-2,2′-bipyridine (dmb) and 4,4′-bis(trifluoromethyl)-2,2′-bipyridine ({CF 3 } 2 bpy), as well as 2,2′-bipyridine (bpy), were used as peripheral ligands on the Ru moiety. Greatly improved photocatalytic activities were obtained only in the cases of [Ru{bpyC 3 bpyRe(CO) 3 Cl} 3 ] 2+ (RuRe 3 ) and the binuclear complex [(dmb) 2 Ru(bpyC 3 bpy)Re-(CO) 3 Cl] 2+ (d 2 Ru−Re), while photocatalytic responses were extended further into the visible region. The excited state of ruthenium in all Ru−Re complexes was efficiently quenched by 1-benzyl-1,4-dihydronicotinamide (BNAH). Following reductive quenching in the case of d 2 Ru−Re, generation of the one-electron-reduced (OER) species, for which the added electron resides on the Ru-bound bpy end of the bridging ligand bpyC 3 bpy, was confirmed by transient absorption spectroscopy. The reduced Re moiety was produced via a relatively slow intramolecular electron transfer, from the reduced Ru-bound bpy to the Re site, occurring at an exchange rate (∆G ∼ 0). Electron transfer need not be rapid, since the rate-determining process is reduction of CO 2 with the OER species of the Re site. Comparison of these results with those for other bimetallic systems gives us more general architectural pointers for constructing supramolecular photocatalysts for CO 2 reduction.

A round robin for the performance of roll-to-roll coated flexible large-area polymer solar-cell modules involving 18 different laboratories in Northern America, Europe and Middle East is presented. The study involved the performance measurement of the devices at one location (Risø DTU) followed by transportation to a participating laboratory for performance measurement and return to the starting location (Risø DTU) for re-measurement of the performance. It was found possible to package polymer solar-cell modules using a flexible plastic barrier material in such a manner that degradation of the devices played a relatively small role in the experiment that has taken place over 4 months. The method of transportation followed both air-mail and surface-mail paths

With the purpose of studying the effect of stabilizing film morphology on polymer photovoltaic cell performance, the morphology and characteristics of bulk heterojunction devices fabricated using binary blends of an azide-functionalized graft copolymer of poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl C61-butyric acid methyl ester (PCBM) were examined. A thermal, solid state reaction between the azide groups attached to P3HT and PCBM, confirmed by Fourier transform infrared spectroscopy (FTIR) and UV−vis spectrocopies, rendered the films largely insoluble and stabilized the morphology, as evidenced by limited growth of macroscopic crystals of PCBM over time, although transmission electron microscopy (TEM) analysis revealed no dramatic changes in morphology at the nanoscopic level. Photovoltaic (PV) devices prepared from these stabilized layers exhibited 1.85% power conversion efficiencies (PCE) which fell to 0.93% over 3 h at 150 °C, whereas native P3HT/PCBM devices, initially displaying 2.5% PCE dropped to 0.5% over the same period. The extent to which the morphology of the bulk heterojunction can be stabilized by this route is discussed.

The need for transparent conductors (TCs) that are capable of withstanding high mechanical deformation in comparison to the brittle indium tin oxide (ITO) films is paramount for roll‐to‐roll production of flexible and stretchable displays, signage systems, lighting devices and solar panels with stringent weatherability requirements. This paper reports a highly stretchable TC comprising of a web of core‐shell nanofibers, which mimics the fibrous structure of natural systems such as veins of a leaf or nerve systems. The TC web demonstrates high transparency, low sheet resistance, and unprecedented stretchability and stability over repeated stretching. The nanofiber TC web can be transferred to different substrates, which is manifested by the transfer onto an organic solar cell, demonstrating a photovoltaic performance comparable to that of a device with an ITO electrode. This work presents a technological platform, scalable for the manufacturing of large area transparent conductors for flexible and stretchable displays, electronics and solar cells on unconventional substrates such as rubber, fabric and paper.

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Poly(3‐hexylthiophene) was quantitatively brominated and subsequently used in the Suzuki cross‐coupling with a boronic ester of a nitroxide to form a macroinitiator bearing a TEMPO group on each thienyl ring. This macroinitiator initiated the nitroxide‐mediated radical polymerization of styrene and 4‐chloromethylstyrene (CMS), and subsequently reacted with C60 to yield soluble graft, rod‐coil polymers. Films of the polymers display a bi‐continuous phase structure as revealed by AFM. Similar polymers, in which only a fraction of the thienyl units boasted C60‐bearing side chains, displayed optical properties representative of extensive π‐delocalization. The potential application of this methodology for the synthesis of graft polymers for photovoltaic devices is discussed.

New Ru polypyridine complexes [(bpy)2Ru(L)]2+, where bpy = 2,2'-bipyridine and L = dipyrido[3,2-a:2',3'-c]-phenazine-2-carboxylic acid (dppzc), dipyrido[3,2-f:2',3'-h]quinoxaline-2,3-dicarboxylic acid (dpq(COOH)2), 3-hydroxydipyrido[3,2-f:2',3'-h]quinoxaline-2-carboxylic acid (dpq(OHCOOH)), 2,3-dihydroxydipyrido[3,2-f:2',3'-h]quinoxaline (dpq(OH)2), and [(L')Ru(dppzc)2]2+, where L' = bpy and 1,10-phenanthroline (phen), have been synthesized, characterized, and anchored to nanocrystalline TiO2 electrodes for light to electrical energy conversion in regenerative photoelectrochemical cells with I-/I2 acetonitrile electrolyte. These sensitizers have intense metal-to-ligand charge-transfer (MLCT) bands centered at approximately 450 nm. The effect of pH on the absorption and emission spectra of these complexes consisting of protonatable ligands has been investigated in water by spectrophotometric titration. The excited-state pKa values are more basic than the ground-state ones, except the pKa2 and pKa2* in [(bpy)2Ru(dpq(OH)2)]2+, which are equal, suggesting the localization of the lowest-energy MLCT on heteroaromatic bridging ligands, dppzc and dpq. Incident photon-to-current conversion efficiency (IPCE) is sensitive to the structural changes that resulted from introducing different functional groups, used for grafting.

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