We have numerically studied the dependence of the photogeneration efficiency of free charge carriers on different radii distribution functions in the framework of the Onsager theory. The distribution function of the thermalization distance greatly influences the form of the theoretical curve. Disorder in the system considered could be beneficial for the photogeneration of charge carriers. Further, the dielectric constant was found to have a great effect on the photogeneration process, especially at low fields. We propose that one possible way of improving the quantum yield of the photogeneration of charge carriers is using a material of high dielectric constant.