High-throughput determination of structural phase diagram and constituent phases using GRENDEL.

Advances in high-throughput materials fabrication and characterization techniques have resulted in faster rates of data collection and rapidly growing volumes of experimental data. To convert this mass of information into actionable knowledge of material process-structure-property relationships requires high-throughput data analysis techniques. This work explores the use of the Graph-based endmember extraction and labeling (GRENDEL) algorithm as a high-throughput method for analyzing structural data from combinatorial libraries, specifically, to determine phase diagrams and constituent phases from both x-ray diffraction and Raman spectral data. The GRENDEL algorithm utilizes a set of physical constraints to optimize results and provides a framework by which additional physics-based constraints can be easily incorporated. GRENDEL also permits the integration of database data as shown by the use of critically evaluated data from the Inorganic Crystal Structure Database in the x-ray diffraction data analysis. Also the Sunburst radial tree map is demonstrated as a tool to visualize material structure-property relationships found through graph based analysis.

Combinatorial solar cell libraries for the investigation of different metal back contacts for TiO2-Cu2O hetero-junction solar cells.

Here we present a comprehensive investigation of TiO2-Cu2O hetero-junction solar cells with different back contacts (Au, ITO, Cu or Ag). Combinatorial hetero-junction libraries consisting of a linear TiO2 thickness gradient produced by spray pyrolysis and a bell shaped Cu2O profile synthesized by pulsed laser deposition were chosen to investigate the impact of the two metal oxide layer thicknesses. The back contacts were deposited as round patches onto a grid of 13 × 13 points, 169 contacts for each contact material, forming a library containing 4 × 13 × 13 = 676 back contacts. Each back contact represented a solar cell with an individual TiO2 and Cu2O thickness. I-V measurements show that all four materials provide an ohmic contact and that the open circuit voltage of ∼300 mV is rather independent of both layer thicknesses and contact material. The size of the Cu2O crystals drastically decreases with distance from the center of deposition, which leads to a drastic increase of series resistance when the crystal size is <50 nm.

UV-Vis-NIR spectroelectrochemical and in situ conductance studies of unusual stability of n- and p-doped poly(dimethyldioctylquaterthiophene-alt-oxadiazole) under high cathodic and anodic polarizations.

Combined CV studies and UV-Vis-NIR spectroelectrochemical investigations revealed an unusual stability of the p- and n-doped PMOThOD in the wide potential window of 4 V. The n-doping process occurs in this polymer down to -2.7 V (vs. Ag/Ag+) in a non-destructive way with the characteristic development of the omega3 transition as a function of the doping level. In situ electronic transport studies revealed a high conductivity of the n-doped polymer which implies high mobility of the negatively charged carriers in the freshly doped PMOThOD film electrodes. An increase in the cathodic polarization, long-term cycling of the film electrodes, especially of higher thickness, results in a growing contribution of the negatively charged carriers trapping to the redox properties of the PMOThOD. The trapping of the charged carriers reduces gradually the electronic conductance of the PMOThOD film, but its effect on the redox-capacity of the film (in a typical scan rates range up to 50 mV s(-1)) is only minor.

Energetics of nanocrystalline TiO2.

The energetics of the TiO(2) polymorphs (rutile, anatase, and brookite) were studied by high temperature oxide melt drop solution calorimetry. Relative to bulk rutile, bulk brookite is 0.71 +/- 0.38 kJ/mol (6) and bulk anatase is 2.61 +/- 0.41 kJ/mol higher in enthalpy. The surface enthalpies of rutile, brookite, and anatase are 2.2 +/- 0.2 J/m(2), 1.0 +/- 0.2 J/m(2), and 0.4 +/- 0.1 J/m(2), respectively. The closely balanced energetics directly confirm the crossover in stability of nanophase polymorphs inferred by Zhang and Banfield (7). An amorphous sample with surface area of 34,600 m(2)/mol is 24.25 +/- 0.88 kJ/mol higher in enthalpy than bulk rutile.