Toshio Enokida

Red electroluminescence and photoluminescence properties of a reduced porphyrin compound, tetraphenylchlorin

Abstract We report red PL and EL properties of a reduced porphyrin, tetraphenylchlorin (TPC). In monomer solution TPC emitted a red PL band at 655 nm. In solid mono-film TPC emitted a red PL band at 660 nm but it also emitted two far-red PL bands at 725 and 750 nm due to aggregated emission sites in the film. EL devices in which TPC were doped at concentrations of 1.6–3.7 wt.% within an Alq 3 host layer showed red EL color due to a 660-nm emission of TPC monomer with a width of 20 nm. The red-emitting devices using α-NPD as a hole-transport layer had maximum luminance higher than those using TPD did. Among the red devices, we obtained a maximum luminance of 520 cd/m 2 with chromaticity coordinates of x =0.620 and y =0.31.

Morphology and hole transport of butadiene derivative

Morphology and hole‐carrier mobilities of 1,1‐bis(p‐diethyl‐aminophenyl)‐4, 4‐diphenyl‐1, 3‐butadiene (DEAB) derivative have been investigated. Annealing on a DEAB film and the temperature of glass transition, crystallization and the melting point on this amorphous film were measured by a differential scanning calorimeter and their polymorphic states discussed. Hole‐carrier mobilities in excess of 10−3 (cm2/V s) have been observed at room temperature. The electric field and temperature dependences of the hole mobility can be described as exp(βE1/2) and exp(T0/T)2 and are discussed according to Arrhenius, Poole–Frenkel formulations and non‐Arrhenius type of temperature dependence assuming Gaussian distribution of the hopping sites.

Electrophotographic properties and ultraviolet light fatigue of dual‐ layered photoreceptors incorporating phthalocyanine and hole transport polymers

Dual‐layered photoreceptors incorporating τ‐form metal‐free phthalocyanine (τ‐H2Pc) for charge generation material and poly(methylphenylsilylene)(PMPS) for charge transport material(CTM) have been studied concerning their electric properties especially in the electrophotographic characteristics. The photoreceptor using PMPS exhibited high sensitivity; however, the fatigue due to ultraviolet(UV) light was observed. We compared them with well‐known poly(N‐vinylcarbazole) for CTM based on surface potentials, sensitivities, hole carrier mobilities, and conductivities. As a result of Gel permeation chromatography, Fourier transform infrared and x‐ray photoelectron spectroscopy spectra before and after UV light irradiation, the PMPS was cleaved into lower molecular weight products and polymerized, which included cross‐linking.

Polymorphic Identification of Oxotitanium Phthalocyanines by Solid-State 13C-NMR Spectroscopy

The polymorphic characteristics of five polymorphs of oxotitanium phthalocyanine (TiOPc; amorphous, α, β, γ and the m-form) have been investigated by means of solid-state cross-polarization magic-angle-spinning (CP/MAS) 13C-NMR spectroscopy. The solid-state CP/MAS 13C-NMR spectra have suggested magnetic differences in the TiOPcs. The well-separated chemical shifts mean superior regularity of the TiOPc molecules.

Temperature Dependences of 13C-NMR Spectra and Conductivities with Metal-Free Phthalocyanines Dispersed in Bisphenol-A-Polycarbonate

Temperature dependences of conductivities of the thin films with α-, β-, τ- and X-forms metal-free phthalocyanines (H2Pcs) dispersed in bisphenol-A-polycarbonate and solid-state cross-polarization magic-angle-spinning (CP/MAS) 13C-NMR of H2Pcs were measured. The activation energies at higher (T>300 K) and lower (T<200 K) temperature region could be calculated in the range of 140 and 373 K. 13C-NMR spectra of the H2Pcs indicated the apparent differences, furthermore, individual spectra were changed at the function of temperature due to the influences by the N-H tautomerism in the H2Pc molecules.

The thermally stimulated current of β-form oxotitanium phthalocyanine dispersed in polyester

A thermally stimulated current (TSC) has been applied to estimate the trap properties on a thin film of β‐form oxotitanium phthalocyanine (β‐TiOPc) dispersed in polyester. The hole trapping levels derived from the activation energies (Eas) were obtained by an initial rising method and heating rate dependence on TSC peaks. The Eas for an electric field of 2.5×103 V/cm were distributed from 0.033 eV for shallow traps to 0.42 eV for deep traps.