Abstract:The syntheses of several new zinc compounds with 1,1′-bis(phosphino)ferrocene ligands and their phosphine chalcogenide derivatives are reported. The X-ray crystal structures

Both the nature of the excited state and the morphology of the active layer combine to greatly influence the efficiency in all-small-molecule organic photovoltaic devices. Hence, squaraines, for which synthesis is simple, reproducible, and low-cost, will be favored active layer materials for commercialization when their higher device efficiencies can be correlated with phase separation, miscibility, and crystallinity. Here, multiple measurement methods are used to provide a self-consistent framework that connects active layer morphology, excited-state populations, and device efficiency. Thin-film thickness is accurately measured with atomic force microscopy, which leads to the extinction coefficient for absorption. Spectroscopy is subsequently used to measure populations of electronic states as squaraines are blended with varying amounts of [6,6]-phenyl C 61 butyric acid methyl ester (PCBM). The populations interchange between such observed states as monomers in dilute mixtures, dimers in concentrated mixtures, and chargetransfer H-aggregates in pure/crystalline regions. The measured efficiency of devices is shown to correlate with these changing populations. A model is presented, which allows for incorporation of DBSQ(OH) 2 molecules within PCBM interstices. The model also accounts for phase separation in as-cast squaraine/PCBM mixtures for concentrations of squaraine above the eutectic point. The increased efficiency achieved through changing excited-state populations informs a process such that devices can be manufactured to have their highest efficiency when their thermodynamically stable state is burnt into the morphology while the device is in use.

Silica bilayers are stable on various metal substrates, including Ru(0001) that is used for the present study. In a systematic attempt to elucidate the detailed structure of the silica bilayer...

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