Fig. 1. Schematic diagram of all-optical synaptic responses and a RNN for image recognition.

Fig. 2. Morphologic and photochromic measurement of CsPbIBr₂ films

Fig. 3. Synaptic behaviors of CsPbIBr₂ films

Fig. 4. Optical pulses and transmittance changes of CsPbIBr₂ films for numbers 6 and 9

Fig. 5. RNN is used to realize visual perception of digital images