Fig. 1. Illustration of the working principle of the filter-array-based reconstructive optical spectrometer. (a) Schematic diagram of the filter-array-based reconstructive optical spectrometer; (b) illustration of the working principle of the filter array; (c) schematic diagram of the discretized spectra

Fig. 2. Absorbance and transmissivity characteristics of the filter array (the numbers of the curves correspond to those of perovskites in Table 1). (a) Absorbance of the filter array; (b) transmissivity of the filter array

Fig. 3. Illustration of the spectormeter and camera characteristics. (a) Quantum efficiency of the CMOS camera; (b) photo of the reconstructive optical spectrometer

Fig. 4. Comparison of the XRD between the Cs_0.1MA_0.9PbBr_1.5I_1.5 obtained by N₂-assisted crystallization method and MAPbBr_1.5I_1.5 obtained by chlorobenzene anti-solvent method

Fig. 5. SEM of Cs_0.1MA_0.9PbBr_1.5I_1.5 film obtained by different methods. (a) Chlorobenzene anti-solvent method; (b) N₂-assisted crystallization method

Fig. 6. Comparison of time course photoluminescence spectra of different films. (a) Time course photoluminescence spectrum of MAPbBr_1.5I_1.5; (b) time course photoluminescence spectrum of Cs_0.1MA_0.9PbBr_1.5I_1.5+2PACz

Fig. 7. Schematic diagram of the optics for spectrometer tests using a Xe lamp with a monochromator

Fig. 8. Reconstruction of the monochromatic spectrum. (a) Comparison between the original and reconstructed spectrum of the monochromatic light with a center wavelength of 500 nm; (b) comparison between the original and reconstructed spectrum of the monochromatic light with a center wavelength of 600 nm

Fig. 9. Comparison between the original and reconstructed spectrum of the broad-band white light from a flashlamp

Table 1. Value of x and y in Cs_0.1MA_0.9Pb(Cl_xBr_yI_1－x－y)₃