Multimodal photodetectors with vacuum deposited perovskite bilayers

Color discrimination and selective wavelength photodetection are crucial for many imaging applications. The most common method to achieve a narrowband spectral response is the combination of optical bandpass filters with broadband photodetectors. However, these devices can only operate in narrowband mode. In this study, we developed a photodetector that operates in broadband and narrowband modes depending on the illumination side. To achieve bifunctional behavior, two perovskites with different bandgaps were integrated in the device, where one of them acts as an optical filter. The broadband response is obtained via illuminating from the side of the lower bandgap perovskite, deposited on the transparent substrate. When light is shined through the top perovskite, the spectral response of the photodetector is determined by the bandgap energy difference of the two perovskites, in our case exhibiting a narrowband response with a full width at half maximum (FWHM) below 50 nm centered in the near-infrared region (760 nm).