Bulk heterojunction (BHJ) is one of the most meaningful structures of organic photodetectors (OPDs). It can be achieved by mixing donor and acceptor in a solvent with the aid of a sol-gel method. Furthermore, BHJ has been proven to be a very effective method to adjust the diffusion length of organic semiconductor excitons. The preparation of OPDs with this structure is a very important work. The conjugate polymer donor poly(3-hexylthiophene) (P3HT) and fullerene derivative acceptor [6,6]-benzene C₆₁-butyric acid methyl ester (PC₆₁BM) are used to form the active layer to prepare a binary BHJ OPD, so as to improve the performance of MgZnO ultraviolet photodetector. The results show that the responsivity of the OPD can reach 0.721 A/W, which is about 3.9 times higher than that of MgZnO ultraviolet photodetector. In addition, the OPD exhibits excellent detection ability, better responsivity and high light to dark current ratio.