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Alignment behavior of a discotic liquid crystalline triphenylene (C8OBTP) on substrates coated with self-assembled monolayers (SAMs) of alkanethiol and asymmetrical alkyl disulfide was investigated by polarized microscopy. Discotic nematic (ND) and rectangular columnar (Colr) phases of C8OBTP shows a different alignment behavior depending on the element of SAMs. C8OBTP exhibits a fan-shaped texture on an alkanethiol SAM in Colr phase, while it has a tendency to show a planar alignment on asymmetrical alkyl disulfide SAM. The different elements of the SAM could influence the alignment behavior of discotic liquid crystal distinctly even in columnar mesophase which has highly self-cohesive forces of systems.

The optimal fabrication condition of cytochrome c Langmuir-Blodgett (LB) film was investigated. To verify the pH dependence of cytochrome c film formation, the various π-A isotherms were obtained at pH 6.0, 7.0, 8.0, 9.0, and 10.0, respectively. The cytochrome c LB films were then fabricated onto the quartz substrate, and the deposition of cytochrome c LB films was investigated by UV-visible spectroscopy.

Photoinduced electron transfer in molecular hetero- Langmuir-Blodgett (LB) films consisting of Green fluorescent protein (GFP)/viologe/TCNQ was investigated. In this work, charge transfer process in the molecular hetero-films has been investigated by femto-second transient absorption spectroscopy. Based on the transient absorption in the GFP/viologen/TCNQ series hetero-films, charge transfer from excited GFP to viologen (TCNQ) was observed with subpicosecond time resolution.

The charge transfer characteristics of molecular homo-films composed of green fluorescence protein (GFP) were investigated by time-resolved fluorescence measurement. In this work, time-resolved fluorescence decay of GFP homo film was measured to investigate the solid-state fluorescence lifetime and to observe the charge transfer by using time-correlated single photon counting method (TCSPC).

The charge transfer characteristics of molecular hetero-LB films composed of green fluorescence protein (GFP), viologen, and cytochrome-c were investigated by transient fluorescence measurement. In this work, transient fluorescence decay of GFP homo film and GFP/viologen/cytochrome-c hetero films were measured to investigate the charge separation rate and transport mechanism by using time-correlated single photon counting method (TCSPC).

Ferrocene(1-1′-ferrocene-N-dioctadecyl carboxamide), flavin(7,8-dimethly-10-dodecylisoalloxazine), viologen [N-allyl-N7′-[3-propylamidoN″,N″-di(n-octadecyl)]-4,4′bipyridiumdibromide), and cytochrome c were used as an electron donor (D), sensitize (S), the first electron acceptor (A1), and the second electron acceptor (A2), respectively in fabricating molecular device. Malonic acid or poly-L-aspartic acid were used as a bridging molecule for the adsorption of A2 molecules onto A1 layers. In order to confirm the electron transfer, Scanning tunneling microscopy(STM) investigation was performed.

To make a molecular assembly of cytochrome c onto the Au substrate, the cytochrome c was modified using the 2-succinimidyl-3-(2-pyridyldi-th-io)propionate(SPDP), so the functional group on the cytochrome c surface was modified. And the modified cytochrome c was adsorbed onto the Au substrate. The modified cytochrome c was examined by using UV-visible spectroscopy and FT-IR. Also, the morphology of cytochrome c adsorbed onto the Au substrate was analyzed by Atomic Force Microscopy(AFM).

To improve the stability and durability of organic EL devices, the mixed HTL layer was fabricated by co-deposition of TPD and Alq3 and the EL cell with the mixed HTL was compared with that with the conventional pure HTL. When more than 5 wt% of Alq3 was added in HTL, the increase in surface roughness of IT0 I TPD-Alq3/Alq3 by annealing was found by AFM to be reduced dramatically. In addition, the running durability was significantly improved by addition of a small amount of Alq3 (< 10 wt %), although the EL characteristics of the cells with mixed HTLs were slightly lowered, i.e. I- V and L V curves shifted to the higher voltages.

The change of surface and interface in bilayers of Alq (Tris-(8-hydroxyquinoline) aluminum) / TPD (N,N′-diphenyl-N,N′-bis-(3-methylphenyl)-(1,1′-biphenyl)-4,4′-diamine)-doped polycarbonate (PC) films for organic electroluminescent devices was characterized by atomic force microscopy (AFM), SEM, and fluorescence microscopy, in the temperature range from R.T. to 250 °C under the air. As single layer films, the dip-coated TPD-doped PC film on indium-tin oxide (ITO)-coated glass and the vapor-deposited Alq films on various substrates showed good thermal stability compared with the vapor-deposited TPD film itself. However, in the bilayered structure of Alq / TPD-doped PC films, the Alq film as the overlaying layer was deteriorated readily, which was accelerated with increasing temperature and TPD concentration in the TPD-doped PC film.

The morphological change of vapor-deposited films of TPD (N, N′-diphenyl-N, N′-bis-(3-methylphenyl)-[1,1′-biphenyl]-4,4′-diamine) and Alq3 (Tris-(8-hydroxyquinoline) aluminum) and the interfacial degradation of Alq3/TPD bilayer were characterized by atomic force microscopy (AFM) and fluorescence spectroscopy, respectively, in the temperature range from room temperature to 80°C under an ambient atmosphere. The TPD and the Alq3 film are widely used as a hole transport and an emitter layer, respectively, in an organic electroluminescent device (an indium tin oxide (ITO) coated glass/TPD/Alq3/metal). As the substrate plate, an ITO coated glass or a slide glass was used in this work. The relative photoluminescence (PL) intensities of Alq3 to that of TPD in an Alq3/TPD and a TPD/Alq3 bilayer were increased with time. The changes were accelerated with increasing temperature and ascribed to quenching of photo-excited TPD by Alq3 diffusing into the TPD layer.

Diaminotriphenylamines 4 possessing four different substituents were newly synthesized, and introduced to polyamic acids 6 by the reaction with aliphatic tetracarboxylic dianhydride 5. The LB films of polyimides 8having triphenylamine units were fabricated on a glassy carbon electrode via the LB films of long chain alkylamine salts of 6 to measure cyclic voltammograms. The methoxy substituted triphenylamine afforded the lowest redox potential, that suggested the highest electron density on the nitrogen atom of the triphenylamine. The photoconductive devices (photodiodes) were constructed by the deposition of polyimides which possessed different chemical structure, i.e., triphenylamines as an electron donor (D), tetraphenylporphyrin as a sensitizer (S), and aromatic polyimide as an electron acceptor (A), giving polyimide LB multilayer films. Two types of photodiodes having E/D/S/A and E/A/S/D were prepared on the semitransparent gold electrodes (E). When the methoxy substituted triphenylamine was ...

Simulation of photoelectric conversion in the photosynthetic reaction center by monomolecular layer assemblies of a folded or a linear type A-S-D triad carried out in this laboratory is reviewed. The oriented triad molecule acts as a charge separation unit and is named a molecular photodiode. The combined system with the linear triad and an antenna pigment is also discussed in terms of the charge separation and the light harvesting.