Fig. 4

2D flexible Bi₂O₂Se photodetector arrays. a Photograph of 2D Bi₂O₂Se photodetectors and arrays on mica. Inset shows photoresponse of one typical photodetector when bending the substrate with strain up to 1%. The current show robust increase when illumination of 1200 nm with power of about 100 μW is on. b 2D Bi₂O₂Se photodetector maintains stable photoresponse in air for at least 5 weeks. c Schematic of the single-pixel imaging process. The 2D Bi₂O₂Se photodetector quantify the infrared reflection of the sample structure by measuring corresponding photocurrent. When the structure is scanned, the detector records the magnitudes of reflection signals and process them into image. d Infrared images taken by single-pixel photodetector of 2D Bi₂O₂Se under excitation at λ = 1150 nm. Scale bar, 100 μm. e Optical image of 3 × 5 multi-pixel array of 2D Bi₂O₂Se photodetectors. Scale bar, 10 μm. f The array’s photocurrent mappings are achieved by recording the photocurrents while scanning the array over a pre-focused laser beam with spot size of 1 to 2 μm. By deliberately choosing several channels in a parallel regime, photocurrents from the chosen pixels are recorded and shown in the photocurrent mapping. Here, the resulting photocurrent images with shape of 1, 2, 3, and 4 are taken under illumination of 1550 nm, 1310 nm, 1200 nm, and 665 nm light, respectively