Liquid-feed flame spray pyrolysis (LF-FSP) is a general aerosol combustion route to unagglomerated and often single crystal mixed-metal oxide nanopowders with exact control of composition. LF-FSP of xNi(O 2 CCH 2 CH 3 ) 2 /yAl(OCH 2 CH 2 ) 3 N EtOH solutions at selected x:y ratios provides mixed-metal oxide nanopowders with compositions covering much of the Al 2 O 3 -NiO phase space. All powders were characterized by XRD, BET, FTIR, SEM, TEM, and TGA-DTA. With the exception of pure NiO (specific surface area, SSA, ∼7 m 2 /g), all product powders offer SSAs g 45 m 2 /g (average particle sizes e 30 nm) without microporosity. At NiO/Al 2 O 3 ratios near 1:1, the LF-FSP nanopowders are single phase, bright blue NiAl 2 O 4 inverse spinel. The blue color of these materials is typical of Ni spinels. At higher NiO contents, NiO is the dominant phase with some δ-alumina and intermediate spinels. At low NiO contents, blue powders form but the δ-alumina phase predominates, suggesting incorporation of Ni 2+ in the alumina lattice or formation of traces of NiAl 2 O 4 . Compositions near 20:80 mol NiO/Al 2 O 3 generate an inverse spinel structure, per XRD with peaks shifted ≈4°2θ to higher values from those of pure NiAl 2 O 4 . This contrasts with the published phase diagram, which suggests a mixture of NiAl 2 O 4 spinel, and corundum should form at this composition. This material resists transformation to the expected phases on heating to 1400 °C, indicating a single stable phase which contrasts with the known phase diagram and, therefore, is a new material in NiO-Al 2 O 3 phase space with potential value as a new catalyst.

We describe nickel tetrabenzoporphyrin ͑NiTBP͒ as a solution-processible organic semiconductor. Whereas porphyrins in an unmodified state are typically planar and insoluble, a precursor synthetic route ͑NiCP͒ was used to deposit thin films via solution. Amorphous, insulating thin films of NiCP were deposited, and thermally converted to polycrystalline, semiconducting NiTBP. Films were studied using optical absorption and microscopy, atomic force microscopy, and x-ray diffraction. Highly concentrated NiCP was shown to form large, needle-shaped crystals drop-cast from solution. NiTBP thin-film field-effect transistors fabricated from spun-cast films demonstrated charge-carrier field-effect mobilities on the order of 0.1 and 0.2 cm 2 / V s and accumulation threshold voltages of −19 and −13, in the linear and saturation regimes, respectively.

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A possible relation between a thin-film microstructure and an organic thin-film field-effect transistor ͑OFET͒ behavior is discussed in terms of nonlinearity in the extraction of the device electrical parameters. Staggered source and drain electrode OFETs were fabricated using a soluble precursor form of the organic small molecule semiconductor tetrabenzoporphyrin, and characterized using linear and nonlinear best-fit methods. Linear best-fit models overestimated the field-effect mobility and accumulation threshold voltage when compared to a nonlinear best-fit model that accounts for dispersive charge-carrier transport. The deviation between the methods is found to be consistently less than that for polymer OFETs, as indicated by smaller nonlinearity factors of ␥ = 1.2 and 1.7 in the linear and saturation regimes, respectively. The nonlinear field-effect mobility exhibits a sublinear gate-bias dependence wherein the mobility increases at a slower rate in strong accumulation than near threshold. Furthermore, nonlinear curve fitting indicates lower trap characteristic temperatures as compared to polymer OFETs, and a relatively moderate density of grain-boundary trap states localized at the dielectric interface and in the bulk to be filled before accumulation-related conduction dominates.

Solution-processed organic thin-film field-effect transistors ͑OFETs͒ were fabricated using a precursor form of the organic semiconductor tetrabenzoporphyrin ͑TBP͒ deposited on a thermal silicon oxide gate insulator patterned with nanometer-scale trenches. Thermal conversion of the precursor film to TBP was enhanced by ordered TBP aggregation in the prepatterned trenches, demonstrating precise control and placement of long-and short-range ordering of the organic semiconductor. OFETs with channels parallel to trench direction growth were found to have field-effect mobility approaching one order of magnitude greater than transistors fabricated with the channel oriented perpendicular to dendrimer growth.