Page 76 - Read Online

Page 8 of 22 Na et al. Soft Sci. 2026, 6, 25

Figure 3. Heterojunction-based zero-power optoelectronic synapses. (A) Schematic illustrations of the working mechanism in
heterojunction-based zero-power optoelectronic synapse correspond to the (i) original, (ii) illumination, and (iii) dark state, respectively.
E c, p , E c, n , E v, p , E v, n , E F, p and E F, n represent the bottom of conduction band, top of valence band and Fermi levels of p-type and n-type
semiconductors, respectively; (B) Schematic illustration of the vertically structured zero-power artificial photoreceptor based on the
GaN/BiFeO 3 heterojunction; (C) UV light-induced learning-forgetting-relearning behavior, demonstrating visual memory emulation in the
GaN/BiFeO 3 -based neuromorphic sensor; (D) Visual memory emulation in a UV-sensitive artificial neuromorphic sensor. Subfigures (B-D)
Reproduced with permission [37] . Copyright 2025, John Wiley & Sons; (E) Schematic illustration of the F 16 CuPc/C 8 -BTBT
heterojunction-based zero-power artificial optoelectronic synapse; (F) SRDP triggered by ten consecutive light pulses, with a duration of
50 ms under different pulse frequencies; (G) Schematic illustration of an artificial visual system, in which the front-end signal processing
units are integrated within the image sensor array. Subfigures (E-G) Reproduced with permission [38] . Copyright 2022, John Wiley & Sons;
(H) Cross-sectional SEM image of the ZnO/WO X heterojunction-based zero-power optoelectronic memristor; (I) Photocurrent under
constant light stimuli on a dark background; (J) Photocurrent response of the device under background illumination and flash stimulation,
demonstrating Weber’s law behavior; (K) Schematic diagram of the neuromorphic visual system, consisting of adaptive image
preprocessing using a visual adaptive neuron and image recognition using a spiking neural network; (L) Spontaneous adaptation of
overexposed images based on the experimentally observed frequency-dependent relaxation dynamics of the visual adaptive neuron.
Subfigures (H-L) Reproduced with permission [ 39 ] . Copyright 2025, John Wiley & Sons. UV: Ultraviolet; C 8 -BTBT:
dioctylbenzothienobenzothiophene; SRDP: spike-rate-dependent plasticity; EPSC: excitatory postsynaptic current; PMMA: poly(methyl
methacrylate); ITO: indium tin oxide.