Masao Yoshikawa

Ionization potentials of oligogermanes and polygermanes

Abstract The ionization potentials of gaseous and solid oligogermanes and polygermanes were measured in the 5.31–8.60 eV regions, and were assigned to ionizations from the germanium framework, by ultraviolet photoelectron spectroscopy. The values of ionization potentials were related to the chain length and ring size of oligogermanes and polygermanes.

VALENCE ELECTRONIC STRUCTURE AT THE INTERFACE OF ORGANIC THIN FILMS

Abstract Valence electronic levels at the interfaces of a photovoltaic double-layered organic thin film, fabricated from N,N ′-dimethylperylene-3,4, 9,10-bis(dicarboximide) (DM-PBDCI) as an n-type semiconductor and aluminum phthalocyanine chloride (AlPcCl) as a p-type one, have been examined by UPS employing a spherical-retarding field electron analyzer, and, in particular, thickness dependences of the photoelectron spectra of single- and double-layered films have studied in detail. The electronic structure of a DM-PBDCI film at the interface with a ZnO substrate shows a different behavior from that with a Cu one. An energetic scheme for the interface of an AlPcCl/DM-PBDCI film is proposed on the basis of the obtained results, and it could be considered to be consistent with a conclusion from the theory of p-n heterojunction.

UV photoemission spectroscopic studies on molecular aggregation of triphenylamines dispersed in polycarbonate thin films

Abstract Ultraviolet photoemission spectra of triphenylamine (TPA) derivatives, N(phenyl) 3- n ( p -tolyl) n ( n =0–3), were measured not only in the gaseous and solid states but also dispersed in poly(carbonate) (PC) thin films with a weight ratio 3 5 (for TPA/PC). Correlations of the electronic structure of the composite films with experimental results on electronic transport are studied, and also the degree of dispersion of the guest molecules in the films is discussed in terms of the polarization energy in the organic molecular solids.