Organic solar cells based on poly（N-vinylcarbazole） （PVK）： porphyrin： tris （8-hydroxyquinolinato） aluminium （Alq3） blend p-n junction systems have been fabricated in this work. The roles of the different components in the blend system and of the amount of porphyrin have been investigated. The 5, 10, 15, 20-tetraphenylporphyrin （TPP） and 5, 10, 15, 20-tetra（o-chloro）phenylporphyrinato-copper （CuTC1PP） are used in the solar cells. The results show that TPP is better than CuTC1PP in enhancing the performance of PVK：Alq3 solar cells. When the weight ratio of PVK：TPP：Alq3 is 1：1.5：1, the best performance of solar cell is obtained. The open circuit voltage （Voc） is 0.87 V, and the short circuit current （Jsc） is 17.5 μA·cm-2. In the ternary bulk hereojunction system, the device may be regarded as a cascade of three devices of PVK：TPP, TPP：Alq3 and PVK：Alq3. PVK, TPP and Alq3 can improve the hole mobility, light absorption intensity and electron mobility of the ternary bulk hereojunction system, respectively.
