A bipolar space charge problem for solids including a secondary electron emissionSwistaczB2007In this paper a new mathematical model for a space charge transport through a solid placed between the two electrodes is presented. Using new equations for allowed electron hole transitions, the effect of the light on the electric field distribution and on the shape of current - voltage characteristic is determined. For a space charge distribution some new singular solutions are obtained. Also, some new shapes of current - voltage characteristic with negative resistance are determined. In this paper it is found that the system can act as an n-p-n or p-n or n-n blocking diode.research-article