Abstract: An object of the present invention is to provide a field effect transistor showing high field-effect mobility and a high ON/OFF ratio, which can be produced simply by using a porphyrin compound with excellent crystallinity and orientation. The field effect transistor according to the present invention transistor contains at least an organic semiconductor layer, wherein the organic semiconductor layer contains at least a porphyrin compound and has a maximum diffraction intensity I1 in a Bragg angle (2?) range of 9.9° to 10.4° stronger than a maximum diffraction intensity I2 in a Bragg angle (2?) range of 23.0° to 26.0° in X-ray diffraction using CuK? radiation.

Abstract: An object of the present invention is to provide a field effect transistor showing high field-effect mobility and a high ON/OFF ratio, which can be produced simply by using a porphyrin compound with excellent crystallinity and orientation. The field effect transistor according to the present invention transistor contains at least an organic semiconductor layer, wherein the organic semiconductor layer contains at least a porphyrin compound and has a maximum diffraction intensity I1 in a Bragg angle (2?) range of 9.9° to 10.4° stronger than a maximum diffraction intensity I2 in a Bragg angle (2?) range of 23.0° to 26.0° in X-ray diffraction using CuK? radiation.

Abstract: An electrophotographic photosensitive member, a process cartridge having the electrophotographic photosensitive member and an electrophotographic apparatus are provided. The electrophotographic photosensitive member has a conductive substrate and a photosensitive layer thereon, wherein the photosensitive layer contains a disazo pigment represented by the following formula (1): ##STR1## wherein R.sub.1 to R.sub.8 are the same or different and are each a hydrogen atom, a halogen atom, an alkyl group or an alkoxy group, n is a positive integer, A.sub.1 and A.sub.2 are the same or different and are each a coupler residual group having a phenolic hydroxyl group, and at least one of A.sub.1 and A.sub.2 is a coupler residual group represented by the following formula (2): ##STR2## wherein X.sub.1 is a residual group forming a polycyclic aromatic ring or a heterocyclic ring by condensing with a benzene ring, R.sub.9 and R.sub.

Abstract: An electrophotographic photosensitive member is constituted by disposing a photosensitive layer on a support. The photosensitive layer contains oxytitanium phthalocyanine and a specific disazo pigment of the formula (I) or (II) each characterized by having particular coupler residues. The photosensitive layer may preferably include a charge generation layer and a charge transport layer. The charge generation layer may preferably include a first charge generation layer containing the above disazo pigment of the formula (I) or (II) and a second charge generation layer containing the above oxytitanium phthalocyanine. The electrophotographic photosensitive member including the photosensitive layer described above is usable for providing an apparatus unit and an electrophotographic apparatus showing excellent electrophotographic characteristics such as high photosensitivity, good potential stability in repetitive use and good image-forming properties substantially providing no black spots.

Abstract: An electrophotographic photosensitive member is constituted by an electroconductive support and a photosensitive layer disposed on the electroconductive support. The photosensitive layer contains a specific disazo pigment having a 2,2'-bis-1,3-benzdithiolene-diyl skeleton or a thiophene-diyl skeleton. The photosensitive member is effective for providing a process cartridge and an electrophotographic apparatus respectively including the photosensitive member with an excellent photosensitivity and a stable electric potential in repetitive use.

Abstract: An electrophotographic photosensitive member, comprising: an electroconductive support and a photosensitive layer disposed on the electroconductive support, wherein the photosensitive layer comprises a triazene compound represented by the following formula (1): ##STR1## wherein R denotes hydrogen, a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, or a substituted or unsubstituted aralkyl group.

Abstract: An electrophotographic photosensitive member has an electroconductive substrate and a photosensitive layer formed thereon. The photosensitive layer contains an acetal resin having a component unit represented by the following formula (1): ##STR1## wherein X is ##STR2## R.sub.1 is a substituted or unsubstituted aryl group and a substituted or unsubstituted heterocyclic group; R.sub.2 is a hydrogen atom and a substituted or unsubstituted alkyl group; R.sub.3 is a substituted or unsubstituted alkyl group; A is a substituted or unsubstituted heterocyclic group and ##STR3## R.sub.4 is a substituted or unsubstituted heterocyclic group; R.sub.5 is a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group and a substituted or unsubstituted heterocyclic group; and n and m are each 0, 1, 2 and 3.