K. Kaneto

Dependences of electrical and mechanical properties of conducting polypyrrole films on conditions of electrochemical polymerization in an aqueous medium

Abstract Electrical and mechanical properties of polypyrrole films prepared under various polymerization conditions are studied. The electrical conductivity is found to be increased to higher than 500 S/cm by selecting the polymerization conditions.

Absorption spectra induced by photoexcitation and electrochemical doping in polythiophene

Abstract Changes of absorption spectra in a polythiophene film caused by photo- excitation and electrochemical doping are studied. The photoexcitation and the slight doping reveal that the formation of a shallow polaron is responsible to the carrier transport. The doping also induces a deep polaron which can explain the change of spectra upon doping.

Electrical and optical properties of polythiophene prepared by electrochemical polymerization

Abstract Electrical conductivities and optical absorptions of neutral and oxidized polythiophene films polymerized by the electrochemical method are reported. The electrical conductivity of polythiophene borofluoride film shows metallic value of ca. 100 S cm−1 at room temperature and decreases over 1010 times into semiconductive regime by the electro-chemical or chemical undoping. Absorption spectrum of polythiophene changes by the undoping from the characteristic of metal to interband transition with absorption edge ca. 2.0 eV and maximum absorption coefficient of ∼ 105 cm−1 at 2.7 eV.

Quenching of photoluminescence in poly(thiophene) films by electrochemical doping

Abstract Photoluminescences observed in undoped poly(thiophene) and poly(3-methylthiophene) films decrease in the intensity with a slight blue shift by electrochemical C1O - 4 doping. However, they persist through polaronic states until fairly heavy doping levels of ca. 0.1 per thiophene ring and are quenched by the onset of metallic state.

A highly conducting poly (p-Phenylene) film

Polymerisation electrolytique du benzene et du diphenyle en solution electrolytique de benzonitrile contenant CuCl 2 et LiBF 4 . Conductivite electrique superieure a 100 s/cm

Emission Spectra of Phthalocyanine Crystals

The emission spectra of phthalocyanine single crystals and evaporated films were investigated in the near infrared. In a H 2 Pc single crystal, several fluorescence peaks were observed between 760 mµ∼1 µ. In a CuPu single crystal, one phosphorescence band with fine structures was observed at 1.12 µ. However, no fluorescence was observed between 700 mµ∼1 µ. In ZnPc single crystals, both the fluorescence peaks and the phosphorescence peak at 1.15 µ were observed. In CoPc and NiPc, no emission was observed. These emission spectra were discussed in connection with S-T interaction caused by central metals. The phosphorescence was decreased markedly with raising temperature. In the evaporated film, a fairly broad emission band was observed which was attributed to the excimer emission tentatively. By the thermal treatment of this film, this broad band changes to the emission band of the single crystal.

Electrical and optical properties of electrochemically prepared polyselenophene film

Abstract The electrical, optical and magnetic properties of flexible shiny films of polyselenophene obtained by the electrochemical method are studied. The electrical conductivity of doped polyselenophene is found to be much lower than that of polythiophene and polypyrrole, which is consistent with its relatively wider ESR linewidth even after doping. The photovoltaic effect is also observed in this polymer and discussed in comparison with optical absorption spectra.

Electrical and optical properties of polaronic states in conducting polymer, polythiophene

Abstract The ESR spin density and linewidth in a slightly BF4− doped polythiophene film decrease upon illumination of an infrared light. The photocurrent response is observed at the infrared region too. The results are discussed in terms of the photoexcitation of polarons to free state and the formation of spinless bipolarons. The evolution of polaronic states during the electrochemical cycle was investigated in detail by the in situ measurement of absorption spectra combined with cyclic voltammogram.

Degradation of polythiophene film by doping-undoping cycle

Abstract The degradation of polythiophene film was studied by XPS. The degraded sample was prepared as follows: a polythiophene / ITO as a working electrode, a Ni plate as a counter electrode, LiBF 4 (0.5M) / acetonitrile as electrolytic solution. The system was derived by applying the 0.5Hz rectangular pulse in a range of −2 to +4V repeating 1.35×10 5 times. The chemical shift of C(1S) was studied by the peak synthesis. C(1S) shifted by F − was observed at 289.6eV, this peak in the degraded sample is remarkably increased in comparison with the doped sample and the undoped sample. The depth profile was studied. F and B were detected in the doped sample, F was detected, but B was not detected in the degraded sample. Therefore, the degradation of polythiophene film is caused by F − which might be formed by the hydrolysis of BF 4 − . This reaction reaches the inside of polythiophene film.

Applications of conducting polymers as electronics and opto-electronics devices

Abstract Various type of electronics and opto-electronics devices like diode, field effect transistor, optical color switching element and erasable optical recording memory element are fabricated. Doping characteristics and mechanism, which are most important to establish high performance of these devices, in a conducting polymer film and composite films are studied as the function of thickness, voltage and solvent etc. The approaches to improve cycle life and response time of color switching cell are discussed in terms of these fundamental studies.