Abstract: An electrophotographic light sensitive element is disclosed. The element is comprised of a photoconductive support base having provided thereon a disazo compound dispersed in a binder or a charge carrier-transporting medium. A novel group of disazo compounds are disclosed as represented by the general formula (I), (II) and (III) as defined within the specification. In addition to the light sensitive element the disazo compounds and electrophotographic compositions containing them are part of the invention disclosed. The electrophotographic light sensitive elements have high sensitivity and long durability.

Abstract: Disazo compounds as well as the compositions and electrophotographic light-sensitive materials utilizing them are disclosed. The disazo compounds are represented by the general formula (I): ##STR1## wherein the substituents within general formula (I) are defined within the specification. By utilizing the specifically disclosed disazo compounds the electrophotographic light-sensitive material has high sensitivity and high durability.

Abstract: A photoconductive composition comprising a disazo compound represented by formula (I): ##STR1## and an electrophotographic light sensitive element containing the compound. The element has a high sensitivity and high durability.

Abstract: A thiopyrylium compound having t-butyl groups at the 2- and 6-positions of the thiopyrylium nucleus, having a main absorption near the red region, i.e., 600 to 700 nm but substantially no side absorption near 400 nm, and useful as a sensitizer for a photoconductive composition.

Abstract: An electrophotographic light-sensitive material is disclosed. The material is comprised of a conductive layer containing cuprous iodide and a photoconductive layer. The photoconductive and electrophotographic characteristics are improved by forming a gelatin interlayer between the conductive layer and the photoconductive layer. The electrophotographic light-sensitive material can be used with either positive polarity or negative polarity.

Abstract: A thiopyrylium compound having t-butyl groups at the 2- and 6-positions of the thiopyrylium nucleus, having a main absorption near the red region, i.e., 600 to 700 nm but substantially no side absorption near 400 nm, and useful as a sensitizer for a photoconductive composition.

Abstract: A photoconductive composition for electrophotography containing a photoconductive material, a sensitizing dye comprising a specific very stable sensitizing dye for red light to infrared rays, and a film-forming polymer binder.

Abstract: 2,6-Di-tert-butyl-4-methyl thiopyrylium salt of the formula (I): ##STR1## wherein Z.sup..crclbar. is an anionic function and certain intermediates encountered in its synthesis.