Patent ID: 7141341

Claim:
An electrophotographic photosensitive member comprising: (a) a support, (b) a charge generation layer containing a charge-generating material and an electron-transporting material, provided on the support, and (c) a charge transport layer containing a hole-transporting material, provided on the charge generation layer, wherein: where in a light attenuation curve drawn in a way in which the surface of the electrophotographic photosensitive member is so charged that intensity of an electric field applied to the electrophotographic photosensitive member is 15 (V/μm) to establish a surface potential of the electrophotographic photosensitive member into a given value E(V) and subsequently the surface of the electrophotographic photosensitive member is exposed to light under conditions that the electrophotographic photosensitive member has a surface potential of 0.8 E(V) at a time point that T(ms) passes after exposure starts, an inclination of the light attenuation curve at a time point that T(ms) passes after exposure starts is represented by m; and in a dark-time surface potential attenuation curve drawn in a way in which the surface of the electrophotographic photosensitive member is charged under conditions that the electrophotographic photosensitive member has a surface potential of 0.8 E(V) at a time point that T(ms) passes after charging is finished and thereafter no exposure is performed, an inclination of the dark-time surface potential attenuation curve at a time point that T(ms) passes after charging is finished is represented by m′, m and m′ satisfy the following expression (I): |m−m′|≦ 0.020 (I), provided that T=((d 2 /(μ×E))×100)×10 −5 , where d is the layer thickness (μm) of the charge transport layer and μ is a drift mobility (cm 2 /(V.s) of the charge transport layer, wherein where the electron affinity of the electron-transporting material contained in said charge generation layer is represented by E A and the electron affinity of the charge-generating material in the charge generation layer is represented by G A , E A and G A satisfy the following expression III: −0.20≦( E A −G A )≦0.20 (III) wherein the charge generation layer is in a layer thickness from 0.01 mm to 2 mm, and wherein the electron-transporting material in the charge generation layer is in a proportion from 10% to 60% by weight based on the weight of the charge-generating material in the charge generation layer.