Visual acuity is the ability of the biological retina to distinguish images. High-sensitivity image acquisition improves the quality of visual perception, making images more recognizable for the visual system. Therefore, developing synaptic phototransistors with enhanced photosensitivity is crucial for high-performance artificial vision. Here, organic synaptic phototransistors (OSPs) based on p-n type semiconductor heterojunctions are presented, which demonstrate improved photoresponses and light storage characteristics. As many as 800 potentiation-depression states can be obtained, and the nonlinearity extracted from the long-term potentiation curve is only 0.08. Furthermore, by utilizing light-adjustable synapse-like behaviors, the phototransistors realize a noise reduction function and logic gate transformation. Benefiting from the enhanced photosensitivity of the OSPs, an artificial neural network constructed based on the OSPs shows the recognition accuracy of ∼93% for both handwritten numbers and electrocardiography signals. This research provides an effective path for developing OSPs with enhanced photoelectric performance to advance artificial visual systems.