Low-Noise Electrically Modulated Dual-Mode Photodetectors with Perovskite/Organic Dual Absorption Layers

Photodetectors with tunable spectral detection ranges have attracted significant attention for advanced optoelectronic applications such as self-aligned multispectral imaging, object identification, and encrypted communication. Here, based on a vertically stacked perovskite/organic (FA_0.9Cs_0.1PbI_2.85Br_0.15/PM6:BTP-eC9) dual absorption layer, we demonstrate a dual-mode photodetector that can switch between the basic detection band (defined by the perovskite absorber) and the extended detection band (defined by the organic absorber) under an external bias. This photodetector takes advantage of the fact that the free charge generation in nonexcitonic perovskites and excitonic organic semiconductors has dramatically different electric-field sensitivities. Through interfacial engineering, detectors with two and three orders of magnitude lower dark currents in the reverse- and forward-bias regions have been achieved, respectively, which offer improved specific detectivities of >10¹¹ Jones and large linear dynamic ranges of >190 dB in both detection modes, resulting in a minimum detectable light intensity of ∼7.0 pW cm^-2. As a proof of concept, a dual-channel optical communication system for information encryption has been demonstrated using our detector. We demonstrate that using perovskite/organic dual absorption layers can be a general route for developing electrically modulated dual-mode photodetectors with varied spectral response ranges.