Compared with inorganic material photodetectors, photodetectors prepared with organic semiconductor materials have the advantages of simple fabrication process, easy integration, good flexibility, good ductility, and stable performance. However, the External Quantum Efficiency(EQE) and responsivity are usually low due to the thin absorber layer. Therefore, how to maximize the absorptivity of organic thin-film absorber layers with different optical structures has been extensively studied. In this study, a high-response organic photodetector based on a light-management structure was successfully fabricated. The experimental results show that the dark current is as low as 3.2 nA at a bias of -10 V. For the organic absorbing thin layer, good photocurrent responses were obtained at wavelengths from 260 to 980 nm, and a responsivity of 0.03 A/W was especially obtained at 850 nm. Compared with the pristine device, the organic photodetector with the light-management structure significantly increases the responsivity by 530%, an order-of-magnitude increase in specific detectivity, and a 200% increase in overall quantum efficiency. The above experimental results prove that the optical enhancement structure is important to this thin-film absorber photodetector, and its performance can be further improved to be comparable to traditional thick-film absorber photodetectors.