Fig. 1. Schematic of silver island film preparation

Fig. 2. Characterization and simulation of silver island film. (a) SEM image of silver island film; (b) SEM of section at silver island film/perovskite interface; (c) transmission spectra, (d)reflectance spectra, and (e) absorption spectra of silver island film; (f) electric field at resonance (top view) and calculation model (insert)

Fig. 3. Fabrication and operating principle of device. (a) Schematic of fabrication of perovskite photodetector; (b) operation principle of narrowband photodetector

Fig. 4. Characterization of devices under different PMMA thicknesses. (a) Narrowband response versus wavelength; (b) FWHM and photocurrent of perovskite device; (c) transmission spectra of silver island films; (d) XRD spectra of 　perovskite films; (e) magnified view of (110) diffraction peak

Fig. 5. Characterizations of device under different precursor solution temperatures. SEM images of perovskite when temperature of precursor solution is (a) room temperature (～25 ℃), (b) 30 ℃，(c) 40 ℃，(d) 50 ℃，(e) 60 ℃，and (f) 70 ℃，respectively; (g) photocurrent versus temperature of precursor solution when wavelength of incident light is 550 nm; (h) XRD spectra of perovskite films under different precursor solution temperatures; (I) magnified view of (110) diffraction peak

Fig. 6. Effects of spin-coating speed on light propagation path and photocurrent. (a) Schematic of light propagation path in perovskite film; (b) photocurrent versus wavelength under different spin-coating speeds; (c) normalized photocurrent curves and photocurrent curve of Si detector; (d) transmission spectra under different spin-coating speeds; (e) optical images of samples under different spin-coating speeds

Fig. 7. Device characterizations. Photocurrent under (a) complete or (b) single switching period; (c) photocurrent; (d) external quantum efficiency; (e) responsivity; (f) normalized detectivity