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Atomic charges are evaluated for molecules used in organic photoconductor applications, the carrier-generation molecule chlorodiane blue (CDB) and the hole-transport molecule p-(diethylamino)benzaldehyde diphenylhydrazone (DEH). Atomic charges are evaluated from experimental X-ray photoelectron spectroscopic data via a fit to an electrostatic potential model and compared to ab initio population analyses using Mulliken, natural orbital, and CHELPG methods and semiempirical CNDO. The observed chemical shifts in the experimental core level binding energies are correlated to the computed atomic charges.

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Longitudinal electron drift mobility of hydrogenated amorphous silicon/silicon nitride multilayer structures revealed by timeofflight measurements Appl.The film thickness, chemical state, and polarization screening for a-SiN 14 :H films deposited by glow discharge over hydrogenated amorphous silicon (a-Si:H) were determined by x-ray photoelectron spectroscopy (XPS) and Auger spectroscopy. The nitride films were observed to be single phase and the escape depth for 1400-eV electrons in the a-SiNJ.4:H film was determined to be 30 A. The band offsets for the a-Si:HI a-SiN 1.4 :H interface were determined by XPS and Bremsstrahlung isochromat spectroscopy (BIS) to be 1.2 eV for the valence band and 2.2 eV for the conduction band, while the band gap for a-SiN L4 :H was found to be 5.3 eV in accordance with the optical gap. By combining optical absorption measurements with the valence-band density of states and conduction-band density of states determined by electron spectroscopy, a semiquantitative estimate of the band tailing within the nitride gap was obtained. Correlation of the defect absorption with the electron spin resonance measurements suggest that the dangling bond defect level in a-SiNI.4:H lies approximately 2.5 eV from the nitride valence band and is, therefore, somewhat below the a-Si:H conduction band. This study has demonstrated that BIS is an effective technique for determining the conduction-band offsets in heterostructures without relying on valence-band offset or band-gap measurements.

Thin films (0.5–2 μ) of CuInSe2 were prepared by spray pyrolysis from solutions with various pH levels and initial Cu:In ratios, and in which the Cu source was either CuCl or CuCl2. The substrate temperature was varied between 225 and 300 °C. All films prepared with CuCl2 were chalcopyrite, while only Cu-rich CuCl based films exhibited this phase. The appearance of Cu2−xSe and/or Cu2/Se as a second phase was found to depend strongly on solution stoichiometry, pH, temperature, and substrate. Two layer structures consisting of a Cu-deficient layer on top of a Cu-rich layer were produced without the presence of any second phases on both glass and Mo-coated glass. This is the first time single phase chalcopyrite Cu-deficient layers have been fabricated by spray pyrolysis. A CuInSe2/CdS photovoltaic cell made from a single phase double layer filme on glass gave a Voc of 0.558 V after heat treatment. This Voc is higher than any reported to date. Absorption spectra have also been measured, and are found to improve when CuCl2 is used instead of CuCl.