Influence of charge mobility of n-type organic semiconductors for the performance of organic p-n junction type photovoltaic devices has been studied. Two n-type organic semiconductors with same main moiety (i.e., perylenebiscarboximide derivates), which posses similar HOMO, LUMO and band gaps; however with different charge mobility especially electron mobility have been utilized in this study. The electron mobility was measured by time of flight method. The electron mobility difference was caused by molecular packing characteristics since one of the semiconductor showed a liquid crystalline behavior.