Atomic Layer Deposited Pd Nanoparticles in TiO 2 Thin Film Enabling Selective Photoresponse for Visual Nociceptor

The blue light spectrum (415–455 nm) penetrates the ocular media to the retina and causes damage to photoreceptor cells, however artificial visual nociceptors specifically responsive to harmful blue light are rarely reported. In this letter, an optoelectronic artificial synapse based on Pd nanoparticles (NPs) in-situ embedded in 20 nm-thick TiO₂ thin film was constructed via atomic layer deposition (ALD). Precise energy band matching enables efficient photo-generated carrier separation and directional transport under blue/green light, leading to enhanced wavelength-selective photoresponse for harmful blue light-responsive visual nociceptors. Furthermore, some key bio-synaptic functions could be also realized in this device with low electrical energy consumption of ~56 fJ per spike. ALD-derived optoelectronic synapse directly couples environmental stimulus perception and injury recognition, paving a competitive avenue for next-generation neuromorphic vision sensors and low-power wearable health-monitoring devices due to its scalable manufacturing capability.