A new model of charge generation process in the single layer organic photoconductor (OPC) was proposed where the charge generation took place at the surface of the photoconductive layer after phonon diffusion from within the photoexcited bulk photoconductive layer. The degradation of the edge sharpness of the electrostatic latent image was simulated theoretically according to this model and the parameters that dominated the resolution degradation in the single layer OPC due to the energy diffusion were determined. The analytical result suggested the model of edge degradation in this system depended strongly on the phonon diffusion length. Accordingly, an experimental analysis was performed that explained the dependence of diffusion length on the photoreceptor formulation. The experimental result showed the validity of the principle in the proposed model for all OPC formulations tested, and the existence of a significant dependence of diffusion length on the CGM concentration in the photosensitive layer. The obtained results numerically showed the superiority in resolution of the single layer OPC compared with those of the conventional dual layer OPC, suggesting the possibility of true 2400 DPI imaging. The results provided a guideline for realizing higher resolution imaging via the single layer OPC formulation.