Photodetectors are one of the most critical components in visible light communication systems. Herein, a broadband photodetector with a structure of FTO/TiO2/Sb2S3/MoO3/Au was proposed. The device performance and its influencing factors were simulated and analyzed using wxAMPS software. By optimizing the material parameters of the absorber layer and the interface characteristics at the TiO2/Sb2S3 and Sb2S3/MoO3 heterointerfaces, the device achieved a responsivity of 0.545 AW-1 and a detectivity as high as 1.116×1014 Jones. These simulation analyses and results provide some reference for the preparation of high performance visible light photodetectors.