Electrophotographic Properties Research Articles

Influence of reactive gas pressure on the deposition of an AlN protective film for organic photoconductor

The deposition of a protective AlN film for hardening and smoothing of organic photoconductor (OPC) surface is an effective method to prolong the operating lifetime of the OPC. In this work, the electrophotographic properties, surface microhardness and surface roughness of AlN coated OPC as a function of N 2 gas pressure during the sputtering of AlN film were systematically studied and optimized. When the N 2 partial pressure increases, the surface roughness increases and the surface hardness decreases. When the N 2 pressure is around 2.7×10 −1 Pa (2 mTorr), the electrophotographic properties reach optimized conditions. When the pressure is increased to 5.3×10 −1 Pa (4 mTorr), the surface roughness increases quickly, the surface hardness decreases, and the electrophotographic properties can deteriorate quickly as a result of the target poisoning phenomenon during the sputtering process. From this work, it is clearly shown that the deposition of AlN protective film can effectively increase the surface hardness of an OPC without causing a deterioration on the electrophotographic properties of the OPC, thereby prolonging the operating lifetime of the OPC. In fact, AIN coated OPC is expected to have a better electrophotographic performance in terms of image development.

Electrophotographic and Hole Transport Properties of Polycarbonates Doped by Organic Photoconductors and Their Light- and Corona Discharge Stabilization

Electrophotographic and hole transport properties of organic photoconductor layers on the base of a phenyltolyl-(β-naphtylamine) (PTNA) doped polycarbonate (PC) and pure (binderless) PTNA were investigated. PTNA was doped into different PCs of types PC-A and PC-Z. Hole drift mobility measured by conventional time-of-flight techniques in the PTNA+PC films was lower than that in the binderless PTNA films. Electrophotographic properties of OPC drums on the base of the PTNA and DEH doped PC layers were studied. An influence of light-, corona- and light + corona intensities on the electrophotographic characteristics of the OPC drums with stabilized or non stabilized charge transporting and generating layers was investigated as well. A stabilization of the electrophotographic layer compounds by various additives such as an antioxidant, an ultraviolet absorber, and an agent for preventing light- and corona induced deterioration was performed.

A new protective AlN film for organic photoconductors

AlN film with high transmissivity was deposited onto organic photoconductor (OPC) surface and the surface hardness was increased by between 31.9% and 61.5%, and the surface roughness was also decreased. The electrophotographic properties of the OPC coated with AlN film were also improved, thus confirming the suitability of AlN film for enhancing the operating life of OPC.

Influence of AIN protective film thickness on the hardness and electrophotographic properties of organic photoconductors

The deposition of a protective film to increase the hardness of an organic photoconductor (OPC) surface is an effective method to lengthen the lifetime of the OPC. In this work, A1N protective films were deposited onto OPC samples by rf reactive magnetron sputtering with low substrate temperature. The A1N films were deposited with optimized sputtering conditions and exhibited very high transmissivity in the visible wavelength range 300-800 nm. The films caused a remarkable increase in the hardness of the OPC surface, by between 32 and 62%. The acceptance voltage, dark decay rate, photodischarge rate, difference between the residual potential and the acceptance voltage of the OPC protected by A1N film were improved. These results show A1N is a suitable protective film for OPC.

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.

Reversible light-induced fatigue of two-layer organic photoconductors studied by time-of-flight photoconductivity measurements

Reversible light-induced fatigue of two-layer organic photoconductors consisting of a charge generation layer (CGL) and a charge transport layer (CTL) was studied by time-of-flight (TOF) photoconductivity measurements. The CGL contains 50% X-metal-free-phthalocyanine in a polyester and the CTL is a solid solution of 33% p-diethylaminobenzaldehyde-diphenylhydrazone in a polyester. Prolonged light exposure under applied fields above 105 V cm-1 causes remarkable changes in electro-photographic properties and the TOF current pulse shape. After light exposure the TOF current increases and the drift velocity of holes through the CTL decreases compared with those before light exposure. From the experimental results, it is concluded that light-induced fatigue of the two-layer photoconductor is a consequence of the build-up of the negative space charge caused by the electron trapping in the CGL and the positive space charge caused by the hole trapping at the CGL-CTL interface. The TOF current waveform strongly reflects the internal potential profile modulated by these space charges. A rest in the dark reverses the TOF current waveforms. The recovery process of TOF waveforms shows that holes trapped at the interface are first released, and then electrons trapped in the CGL are released thermally.

Photoelectret and electrophotographic properties of barium titanate-polyvinylidene fluoride composite film

Photoferroelectric barium titanate (BaTiO3)-polyvinylidene fluoride (PVDF) composite films in the ratio 70∶30 are found to possess good photosensitivity in the visible region of the spectrum. Results on investigations of charge generation, trapping, recombination, discharge and retention properties of the composite film are presented in this paper. Photoinduced polarization is obtained in a BaTiO3-PVDF composite film by the simultaneous application of a d.c. field and illumination from an argon-ion laser or by white light. The dark (photo) polarization and the dark (photo) depolarization current decay characteristics of the polarized films have been studied under different experimental conditions. The studies show that the composite film retains good polarization for a fairly long time in the dark condition, and the magnitude of the depolarization current is comparable with that of BaTiO3 single crystal. Under illumination, the decay is fast enough to make use of the film for electro-photographic applications.

Photosensitivity of selenium-bismuth films with varigap structure

The results of creating and investigating the electrophotographic layers on the basis of selenium-bismuth system with variable bismuth concentration along the thickness of the film are given. The samples for the investigations were obtained by means of thermal coevaporation of components on the oxidized aluminum substrate. Investigation of molecular and electron structure and those of electrophotographic properties of varigap films on the basis of Se-Bi showed the possibility of effective control of both spectral dependence and of absolute values of electrophotographic sensitivity of the films.

Electrical and electrophotographic properties of CdSe/SeTe and CdSe/Se multilayers

Novel amorphous superlattices CdSe/SeTe and CdSe/Se are obtained. Small-angle x-ray diffraction measurements of these structures revealed that high quality super-lattices with smooth interfaces were deposited. Parallel and perpendicular dark currents are measured. The changes of the activation energy and photoconductivity at small sublayer thicknesses are explained with quantum-size effect. The expansion of the spectral sensitivity toward the near-infrared region and fast photo-discharge suggest that a-Se monolayer/superlattice structures would be perspective for electrophotographic and laser printer photoreceptors.

Photoelectret and electrophotographic properties of barium titanate-polyvinylidene fluoride composite film

Photoelectret and electrophotographic properties of barium titanate-polyvinylidene fluoride composite film

Effect of group I and group VI elements on electrophotographic properties of selenium

The effects of group I elements (Li, Na and K) and group VI elements (O and S) on electrophotographic properties of selenium has been systematically investigated by the xerographic measurement technique. It was found that group I and group VI elements show very different effects on the residual potential of selenium. The phenomena could be explained by the modified structural defect model.

Effects of Purification of Phthalocyanine Pigment on an Electrophotographic Properties of Pigment Dispersion-Based Photoreceptor

Effects of Purification of Phthalocyanine Pigment on an Electrophotographic Properties of Pigment Dispersion-Based Photoreceptor

EFFECT OF VARIOUS IMPURITIES ON ELECTROPHOTOGRAPHIC PROPERTIES OF Se AND Se-Te ALLOYS

Abstract Effect of various impurities and additives on electrophotographic properties of Se and Se-Te alloys has been systematically investigated by the xerographic measurement technique. It was found that oxygen has a profound effect on the residual potential of pure Se. In order to find Se-Te alloys with the residual potential as low as possible, various quarternary alloys with V group elements (Bi, Sb) and halogens have been prepared and evaluated. Se-Te-Sb-Cl alloy showed the best electrophotographic properties with the lowest residual potential and dark decay. The experimental results are explained by modifying the structural defect model developed by Kastner et al.

Electrophotographic properties of Se-Te-Sb-Halogen alloy

In order to reduce the residual potential of Se-Te alloy, we clarified the effect of antimony and halogens on the electrophotographic properties of Se-Te alloy. It was found that Se-(13 wt%)Te alloy doped with antimony (1 wt%) and chlorine (20 ppm) had sufficiently low residual potential and they had enough surface potential. It was also found that the addition of antimony improved the thermal stability of Se-Te alloy.

Characteristics and Reliability of Amorphous Silicon Photocnductor Drums for PPC or LBP

The reliability of the a-Si drum has been investigated via environmental tests and durability copy testing, and its electrophotographic properties have been confirmed to be very stable. Regarding imaging properties, a-SiC surface layer plays an important part suppressing the noise within the image. It has been discovered that the blurring of the image in high humidity after many copying cycles is caused by the deterioration of the surface layer which occurs through exposure to corona discharge. This blurring is eliminated by preventing absorption of moisture at the surface, such as heating the drum. In this manner, it has been observed that a-Si drum maintains a high quality image up to 1,000,000 copy sheets.

Electrophotographic Properties of an Organic Photoconductor and a Triboelectric Magnetic Toner for a New Diode Laser Printer

The electrophotographic properties of a newly developed organic photoconductor and triboelectric magnetic toner were investigated for a nonimpact printer with a diode laser. The photoconductor was composed of a metal-free phthalocyanine layer and an oxazole-derivative-doped polymer layer. The photoconductor had a charge acceptance of -1000 V and a light sensitivity of more than 0.1 m 2 /mJ at 780 nm. The magnetic toner had a resistivity as high as 10 14 ? cm and could accept triboelectric charge of -3.5 ?C/g. Chrome dye was employed for a negative charge control agent to affect the sign and magnitude of triboelectric charge on toner particles. Using the developed organic photoconductor and triboelectric magnetic toner, good quality prints on plain paper were obtained with the new diode laser printer. Toner mass density deposited on the photoconductor was improved by more than 20 percent as compared with that of conventionally used conductive or high-resistance magnetic toners. It was found that the triboelectric magnetic toner had a very high transfer efficiency of as large as 80 percent, even on plain paper.

Effect of chlorine in the electrophotographic properties of Se-Te alloy

In order to reduce the residual potential of Se-Te alloy, the alloy is conventionally doped with chlorine in the ranhe from 10 ppm to 500 ppm. However, the addition of large amounts of chlorine decreases the resistivity so that it becomes difficult to maintain the imaging potential. In this study we clarified the effect of small amounts of chlorine (less than 10 ppm) on the electrophotographic properties of Se-Te alloy. It was found that Se-Te alloys doped with about 2 ppm Cl had sufficiently low residual potentials and their dark resistivity was high enough to maintain the imaging potential. It is presumed that the purity of selenium and tellerium is important to obtain the results found in this study.

Effect of oxygen on electrophotographic properties of selenium

To clarify the effect of oxygen, pure selenium was doped with SeO 2 in the range of oxygen content between 3.5 ppm to 1750 ppm and the effect of oxygen was studied by the electrophotographic technique and by the time-of-flight technique. It was found that oxygen has a strong effect on changing the residual potential. The phenomenon can be explained by the change of structural defect density which takes place because of the change of the electrical neutral condition due to the doping of oxygen. From the analysis of the dark decay curve of the residual potential, it was also concluded that oxygen creates shallower levels. The mobility was not affected by the addition of oxygen but the carrier lifetime was decreased with the increase of the oxygen content. This also shows that oxygen creates shallower localized carrier traps in selenium.

Effect of reaction temperature on the average crystallite size of SexTe1−x alloys

Electrophotographic properties of chalcogenide materials are readily influenced by altering their composition and/or structure. Dark decay and cycle down of photoreceptors utilizing small particle generators are both directly proportional to average crystallite size (ACS). This paper describes a novel chemical method to control the ACS of Se, Te, and Sex Te1−x alloys. These chalcogenide materials are prepared as powders by the reduction or coreduction of SeIV and/or TeIV intermediates with hydrazine, in organic media. To control the ACS of precipitated chalcogens the reaction is carried out at the desired temperature. X-ray diffraction measurements are used to determine the ACS, homogeneity, and phase of these precipitated powders.

Effect of Oxygen on Electrophotographic Properties of Selenium

Effect of Oxygen on Electrophotographic Properties of Selenium