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Page 6 of 22 Na et al. Soft Sci. 2026, 6, 25

Figure 2. Schottky junction-based zero-power optoelectronic synapses. (A) Schematic illustrations of the working mechanism in a
Schottky junction-based zero-power optoelectronic synapse correspond to the (i) original, (ii) illumination, and (iii) dark state,
respectively. E c , E v and E F represent the bottom of conduction band, top of valence band, and Fermi level of the semiconductor, respectively.
Φ B0 , V bi and e denote the work function of metal, built-in potential and elementary charge, respectively; (B) Schematic of the Bi 2 O 2 Se-V Se
nanosheet-based zero-power optoelectronic synapse, with the inset highlighting the vacancy-rich atomic structure; (C) I DS depending on
V DS characteristics of the device measured in dark conditions (top) and I DS without bias under illumination at wavelengths of 350, 532, and
1,050 nm (P = 66 μW·cm ), demonstrating broadband photoreception (bottom); (D) Demonstration of high-pass filtering of the device.
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Subfigures (B-D) Reproduced with permission [32] . Copyright 2024, American Chemical Society; (E) Schematic illustration of a 10 × 5 array
of ITO/P3HT/Al zero-power optoelectronic synapse; (F) Representative PSCs induced by two consecutive light pulses (λ = 520 nm, P =
215 mW·cm , duration = 100 ms, interval = 500 ms); (G) Photopic adaptation of the zero-power vision sensor array for pattern
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recognition. Subfigures (E-G) Reproduced with permission [33] . Copyright 2025, American Chemical Society; (H) Schematic illustration of
the Cs 2 AgBiBr 6 -based zero-power photonic synapse; (I) Representative EPSC triggered by 10 light pulses (λ = 445 nm, P = 36.6 μW·cm )
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exhibiting in-sensor reservoir; (J) The weight modulation in the 25 × 4 array before and after the 50 training epochs for vehicle-flow
classification. Subfigures (H-J) Reproduced with permission [34] . Copyright 2022, John Wiley & Sons. Bi 2 O 2 Se-V Se : Bi 2 O 2 Se nanosheet with
selenium vacancies; ITO: indium tin oxide; P3HT: poly(3-hexylthiophene-2,5-diyl); PSCs: postsynaptic currents; EPSC: excitatory
postsynaptic current; P(VDF-TrFE): poly(vinylidene fluoride-trifluoroethylene).