Fig. 1. (Color online) (a) Schematic of a human eyeball and the retinal neuron array. (b) Schematic of an electric eye and the biomimetic nanowire array. (c) SEM image of the nanowire array, the scare bar refers to 1 μm. (d) The XRD pattern of CsPbI₃ nanowires with Pb nano clusters. (e) The XRD pattern of ITO electrodes. (f) The XRD pattern of SnO₂ nanotubes.

Fig. 2. (Color online) The fabrication process of the nanowire array.

Fig. 3. (a) Photo current at 0.01 V under 872 μW/cm² illumination. (b) Photo current at 0.5 V under 143, 325, 573, 742, 872 μW/cm² illuminations, respectively. (c) Photo current at 0.5 V under 872 μW/cm² illuminations with different pulse widths. (d) Photo current at 0.5 V under 10 pulses of 872 μW/cm² illumination. (e) Photo current at 0.5 V under 100 pulses of 872 μW/cm² illumination. (f) Normalized Photo current at 0.5 V under 872 μW/cm² illumination with 1 s pulse width after certain months. The device was kept in indoor environment with a temperature range of 5−35 °C and a humidity range of 30%−80%.

Fig. 4. (a)−(c) Spike frequency-dependent plasticity of the device under 872 μW/cm² optical pulses with the same pulse widths and different pulse intervals at 0.5 V.

Fig. 5. Paired pulse facilitation of the device under 872 μW/cm² optical pulses with (a) shorter and (b) longer pulse widths and pulse intervals at 0.5 V.

Fig. 6. (Color online) Paired pulse facilitation of the device at 0.5 V under 712 μW/cm² optical pulses with wavelengths of (a) 650 nm, (b) 520 nm and (c) 405 nm, respectively.

Fig. 7. (Color online) (a)−(c) Working mechanism of standard mode. (a) Energy band diagram at 0.01 V bias. (b) Energy band diagram at 0.01 V bias under short time illumination. (c) Energy band diagram at 0.01 V bias under long time illumination. (d)−(f) Working mechanism of standard mode. (d) Energy band diagram at 0.5 V bias. (e) Energy band diagram at 0.5 V bias under short time illumination. (f) Energy band diagram at 0.5 V bias under long time illumination.

Fig. 8. (Color online) Imaging process flows of standard and neuromorphic modes.

Fig. 9. (Color online) (a) Schematic of the crossbar image sensor. (b) Schematic of the crossbar image sensor and its read-out circuit. (c) Input optical pattern for the imaging demonstrations. (d) Image acquired by the device under standard mode. (e) Images acquired by the device under neuromorphic mode after 1, 2, and 3 s learning process under exposure, and 1, 2, and 3 s forgetting process in dark environment.