Here, a three-terminal
optoelectronic synapse is simply fabricated based on chitosan (CS)/indium
gallium zinc oxide (IGZO) with a combination of electrical and optical
simulations, which successfully emulates the key features of biological
synapses of learning and memory behavior, in particular the reproduction
of the typical Hebbian spike-time dependence plasticity (STDP) rule
and 2794.6% of the maximum paired-pulse facilitation (PPF) under electrical
stimulation. Creating an analogy to device characteristics, more importantly,
memory behavior was studied with changes of the human internal state
(comfortable and uncomfortable) and the external environment stimuli
(quiet and noise); this showed the best results, longest forgetting
time and good memory effect, under a comfortable internal state and
a quiet environment. Our results suggest that solution-gated IGZO-based
electric-double-layer transparent phototransistor transistors could
act as platforms for synaptic and human behavior simulation.