Growing interest in Fe 2 O 3 as a light harvesting layer in solar energy conversion devices stems from its unique combination of stability, nontoxicity, and exceptionally low material cost. Unfortunately, the known methods for conformally coating high aspect ratio structures with Fe 2 O 3 leave a glaring gap in the technologically relevant temperature range of 170-350 °C. Here, we elucidate a self-limiting atomic layer deposition (ALD) process for the growth of hematite, R-Fe 2 O 3 , over a moderate temperature window using ferrocene and ozone. At 200 °C, the self-limiting growth of Fe 2 O 3 is observed at rates up to 1.4 Å/cycle. Dense and robust thin films grown on both fused quartz and silicon exhibit the expected optical bandgap (2.1 eV). In situ mass spectrometric analysis reveals the evolution of two distinct cyclic reaction products during the layer-by-layer growth. The readily available and relatively high vapor pressure iron precursor is utilized to uniformly coat a high surface area template with aspect ratio ∼150.

A series of cobalt-containing redox couples, based on [Co(1,10-phenanthroline)(3)](ClO(4))(2) and its derivatives, were prepared for use as regenerators/shuttles in dye-sensitized solar cells featuring modified TiO(2) photoelectrodes. Surface modification and trap-state passivation of the TiO(2) nanoparticle film electrodes were accomplished via atomic layer deposition of an ultrathin alumina coating. Electron lifetimes were then extracted from open-circuit voltage decay measurements. Cells employing alumina barrier/passivation layers exhibited higher open-circuit voltages as shuttles with more positive redox potentials were used, with the Co(5-nitro-phen)(3)(3+/2+) couple exhibiting the highest V(oc) (0.844 V). Analysis of the open-circuit voltages and electron lifetimes indicate Marcus normal-region behavior for back electron transfer from the TiO(2) photoanode to these compounds.

The molar absorptivity curves of the mono and bis nickel(II) complexes of 2,2'-bipyridine and 1,10-phenanthroline have been deduced from the composite absorbance data of a series of equilibrium solutions in methanol using equilibrium-restricted factor analysis, a technique for extracting spectral and thermodynamic information for component species involved in solution equilibria. The solutions achieve equilibrium slowly (t(1/2) approximately 100 min) as the amounts of the tris and methanolato complexes are initially in excess. The relative formation constants at 293 K have been determined with a high degree of accuracy, especially for the bipyridine complexes: log(K(1)/K(2)) = 0.340(4) and log(K(2)/K(3)) = 1.091(6). Solubility limitations compromised the accuracy of the thermodynamic results for the phenanthroline complexes.

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