Figure 4: Flexible TMD composite films for band-selective photodetection.

(a) Schematic illustration of the photodetector containing a mixture of MoSe₂ and MoS₂ nanosheets exfoliated with PS-NH₂. (b) Energy dispersive X-ray spectroscopy (EDX) mapping of blended MoS₂/MoSe₂ (5:5), MoSe₂ and MoS₂ films with PS-NH₂. Elemental mapping of the individual atoms in the MoS₂/MoSe₂ (5:5) film are also showed. (Mo, Blue; Se, Yellow; S, Green; C, Red). The Se and S atoms are uniformly distributed over the composite film, which implies that both MoSe₂ and MoS₂ are mixed homogeneously. (In all cases: the scale bar, 2 μm) (c) Photoresponse performance of blended composites with different mixing ratio of MoSe₂ and MoS₂ with PS-NH₂ as a function of wavelength in the visible to NIR. (d) Photocurrent and (e) specific detectivity as functions of the composition of the MoSe₂ and MoS₂ mixtures embedded in PS-NH₂ at wavelengths of 532 nm and 1,064 nm with light intensities of 63 mW cm⁻² and 230 mW cm⁻², respectively. (f) Ratios of the photocurrent to the dark current of the detectors containing MoSe₂, MoS₂ and blended MoSe₂/MoS₂ (5:5) composites with PS-NH₂ as a function of the bending radius. MoSe₂ and MoS₂ composites were examined at a wavelength of 1,064 nm with a light intensity of 230 mW cm⁻² and 532 nm with a light intensity of 63 mW cm⁻², respectively. On the other hand, blended MoSe₂/MoS₂ (5:5) composite film was investigated at both the wavelengths of 1,064 nm and 532 nm with a light intensity of 230 mW cm⁻² and 63 mW cm⁻², respectively. (g) Photographs of in situ measurements of the flexible photodetectors at different bending radii.