Photoconductive Compounds Research Articles

Enhancement of Photosensitivity of Photorefractive Ferroelectric Liquid Crystal Blends to Green and Red Wavelength Regions Using Oligothiophene Photoconductive Dopants

The photorefractive effect can be used to generate rewritable holograms in a material, and it is utilized in various devices, including three-dimensional displays, optical tomography units, novelty filters, phase conjugate wave generators, and optical amplifiers. Ferroelectric liquid crystal (FLC) blends composed of a smectic liquid crystalline mixture, a chiral photoconductive dopant, and an electron trap reagent exhibit significant photorefractivity together with rapid responses. In previous studies, terthiophene derivatives were used as chiral photoconductive dopants and the resulting photorefractive effects were examined at 488 nm. In order to utilize the photorefractive ferroelectric liquid crystals in practical devices such as photoacoustic interferometers and ultrasound imaging units, the wavelength sensitivity of the material should be extended to longer regions. In the present work, chiral dopants possessing quarter-thiophene chromophores, sexithiophenes, and other photoconductive compounds with ...

ChemInform Abstract: CsCdInQ3 (Q: Se, Te): New Photoconductive Compounds as Potential Materials for Hard Radiation Detection.

AbstractCsCdInSe3 (I) and CsCdInTe3 (II) are prepared by reaction of In, Cs2Se3 or Cs2Te3, Cd, and Se or Te in a molar ratio of 2:1:2:3 ((I): 1.

Influence of Photoconductivity on the Photorefractive Effect of Ferroelectric Liquid Crystal Mixtures

The influence of photoconductivity on the photorefractive effect of ferroelectric liquid crystals (FLCs) was investigated. Mixtures of phenylpyrimidine derivatives, a chiral dopant, and a viscosity reducer were used as host FLC materials and two types of photoconductive compounds and an electron acceptor compound were added. The photorefractive effect was evaluated using two-beam coupling experiments. It was found that the magnitude of the gain coefficient was affected by the difference between the mobility of the photoconductive compound and that of the electron acceptor.

Influence of the Physical Properties of Ferroelectric Liquid-Crystal Mixtures on the Photorefractive Effect

The relationship between the thermal properties and the photorefractive effect of various ferroelectric liquid-crystal compositions was investigated. Mixtures of phenyl pirimidine derivatives were used as host liquid-crystal materials to which chiral dopants and photoconductive compounds were added. The photorefractive two-beam coupling gain coefficient was strongly dependent on the magnitude of spontaneous polarization and the uniformity of the surface-stabilized state.

Influence of the Laser Incidence Conditions on the Spontaneous Polarization Reorientation Photorefractive Effect of Ferroelectric Liquid Crystals

The photorefractivity of a ferroelectric liquid crystal (FLC) mixed with a photoconductive compound was investigated in detail. FLCs are anisotropic media, so that laser beam incidence conditions strongly affect the formation of the refractive index grating. Effects of intersection angles of the laser beams, sample angle, sample rotation angle, sample thickness, and polarization of the laser beams on the photorefractivity of FLCs were examined.

Spontaneous Polarization Reorientation Photorefractive Effect in Ferroelectric Liquid Crystals

The photorefractive effect of a series of low-molecular-weight ferroelectric liquid crystals (FLCs) doped with photoconductive compounds was investigated using two-beam coupling experiments. Asymmetric energy exchange was observed only in the ferroelectric phase, and the refractive index formation time was found to be ∼30 ms, which is faster than that of nematic photorefractive LCs. These results indicate that the mechanism of the photorefractive effect in FLCs is different from that in nematic LCs. The photorefractivity of a photoconductive polymer and FLC mixture was also investigated, and the effects of temperature, the strength of the applied electric field and spontaneous polarization on the diffraction efficiency were examined.

Influence of the Properties of Ferroelectric Liquid Crystals on the Spontaneous Polarization Reorientation Photorefractive Effect

The photorefractivity of 14 ferroelectric liquid crystals (FLCs) mixed with a photoconductive compound was investigated by two-beam coupling experiments. The influence of the properties of low-molecular-weight FLCs on the photorefractive effect was examined, and it was found that the photorefractive two-beam coupling gain coefficients and the refractive index grating formation time are strongly dependent on the properties of FLCs. The effects of the magnitude of the spontaneous polarization, the viscosity, and the homogeneity of the surface-stabilized state on the photorefractivities of FLCs are discussed based on these findings.

PD05 強誘電性液晶のフォトリフラクティブ効果 : 光導電性化合物の構造の効果(フォトニクス・光デバイス)

PD05 強誘電性液晶のフォトリフラクティブ効果 : 光導電性化合物の構造の効果(フォトニクス・光デバイス)

Spontaneous Polarization Vector Reorientation Photorefractive Effect in Dye-Doped Ferroelectric Liquid Crystals

The photorefractive effect of a series of low-molecular-weight ferroelectric liquid crystals (FLCs) doped with photoconductive compounds was investigated through two-beam coupling experiments. Asymmetric energy exchange was observed only in the ferroelectric phase, and the refractive index formation time was found to be ∼30 ms, which is faster than that of nematic photorefractive LCs. These results indicate that the mechanism of the photorefractive effect in FLCs differs from that in nematic LCs. The photorefractivity of a photoconductive polymer and FLC mixture was also investigated, and the effects of temperature, the strength of the applied electric field, and spontaneous polarization on the diffraction efficiency were examined.

Spontaneous polarization-vector-reorientation photorefractive effect in ferroelectric liquid crystals

The photorefractive effect of a ferroelectric liquid crystal doped with a photoconductive compound was investigated. The photorefractive effect appeared only at the temperature at which the sample exhibits ferroelectricity. The refractive index grating formation time was measured to be ∼30 ms. In the ferroelectric phase, reorientation of the spontaneous polarization vector was found to be induced by the internal space-charge field.

A Relationship between the Refractive Index and the Infra-Red Threshold of Sensitivity for Photoconductors

It is shown that for photoconductive compounds the long wavelength `threshold' of sensitivity λ should be related to the refractive index n of the photoconductor, and analysis of the available data shows that for the more highly refractive compounds n4/λ always has a value close to 77. As a consequence of this relation, an explanation can be given for the change of the threshold wavelength with temperature which is observed for lead sulphide and similar materials. Suggestions are made as to what materials ought to be suitable for photoconductive detectors at longer wavelengths in the infra-red, and some confirmation of the ideas is shown by results obtained with cadmium arsenide, the properties of which are briefly described