Ultrasensitive Photonic Synapse with Broadband Response Based on the PdSe₂ QDs/GeSe Thin Film

Photonic synapses that integrate optical sensing with synaptic functionalities are becoming increasingly important in the advancement of neuromorphic computing systems. However, achieving broad-band sensing and preprocessing capabilities under weak light illumination remains a significant challenge. Herein, we report a photonic synapse based on the PdSe₂ QDs/GeSe thin film which leverages the high photosensitivity and favorable band alignment of the PdSe₂ QDs/GeSe heterojunction to emulate essential synaptic functionalities. It also exhibits a broadband photoresponse ranging from ultraviolet (UV, 365 nm) to near-infrared (NIR, 850 nm) and maintains performance under an ultraweak light detection threshold down to 0.15 μW cm^-2. Furthermore, its potential applications for optical information processing and facial recognition are demonstrated. This work provides a promising strategy for developing multifunctional photonic synapses based on the PdSe₂ QDs/GeSe thin film.