The discrepancy in the photoresponse characteristics between photodetectors (PDs) and photosynapses is posing a challenge for integrating the two functions into a single device. In this work, a photodetector integrated with neuromorphic capabilities is demonstrated. Under the joint action of the photovoltaic effect and photoconductive effect, the proposed device can switch between the photodetector and photosynapse by simply altering the polarity of bias voltage. Under a reverse or zero bias voltage, the device operates as a photodetector with low dark current and high specific detectivity. On the other hand, when a positive bias voltage is applied, the device showcases synaptic functionalities such as excitatory postsynaptic current, paired-pulse facilitation, and transition from short-term memory to long-term memory. The dual-functional devices hold promise for weak light detection and neuromorphic computing in complex environments.