Flexible photodetector selects wavelengths through electrical control A flexible photodetector using asymmetric 2D heterostructures switches spectral response by gate voltage, enabling filter-free wavelength control under bending. Structure and characterization of the gate-tunable flexible photodetector based on Gr/MoS 2 /SWCNT asymmetric heterostructure. a Schematic of the 3D structure of the flexible photodetector based on Gr/MoS 2 /SWCNT. c Photograph of the flexible photodetector based on PET substrate. e Comparison of Raman spectra of the flexible photodetector based on Gr/MoS 2 /SWCNT and the original MoS 2 film.