Fig. 4: Optoelectronic memory behaviour and neuromorphic applications.
From: Azobenzene-based optoelectronic transistors for neurohybrid building blocks
a Channel current recorded upon the application of a light stimulus (500 light pulses, λ = 365 nm, PW = 1 s, Δt = 1 s) (blue solid line) and a negative voltage pulse (black dashed line, green box). b Series of consecutive negative voltage pulses of increasing intensity from (i) Vgs = −20 mV to Vgs = −120 mV and resulting channel current measurements under (ii) dark and (iii) light conditions. c Schematics representing the mechanism of protons migration from the channel to the electrolyte towards the azo-tz-PEDOT:PSS gate terminal. d Operation of the azo-OPECT as optoelectronic memory (channel conductance measurement): write/erase processes induced by the application of light pulses train (20 light pulses, λ = 365 nm, PW = 2 s, Δt = 10 s) (blue solid line) followed by a negative square voltage pulses train (Vgs = −300 mV, PW = 3 s, Δt = 10 s) (black solid line, green box). e Atkinson-Shiffrin memory model: (i) sensory memory: the sensory information (purple boxes) was rapidly forgotten. The Ids did not reach the memory threshold (horizontal red dotted line), (ii) working memory: a low intensity of light (20%) was applied. Initially, the current overcame the memory threshold. The short-term behaviour was emulated by applying negative square voltage pulses at the gate terminal. As a result, the current value returned below the threshold. (iii) Long-term memory: the high intensity of light (100%), emulating the rehearsal process, induced a current decrease which cross the threshold even when the negative voltage pulses were applied achieving the long-term memory.
