Flexible Photodetectors

We present a flexible photodetector for visible wavelengths fabricated by stacking chemical vapor deposited (CVD) graphene and CVD MoS₂ onto a flexible polyethylene terephthalate (PET) substrate, where MoS₂ acts as an absorber and graphene is used as a conductive channel. When electron-hole pairs are generated in MoS₂ upon illumination of the stack, MoS₂ donates electrons to the p-doped graphene channel [1], resulting in a decrease of the total source-drain current. In this configuration, the device responsivity can be enhanced either by promoting the injection process from MoS₂ to graphene through side-gating using a polymer electrolyte [2, 3], or by applying larger source-drain voltage. The device shows responsivity as high as ~570A/W at 642nm. The reported responsivity is at least two orders of magnitude higher than the values obtained in the bulk-semiconductor flexible membranes [4] and other flexible photodetectors based on graphene and layered materials [5]. The photocurrent is stable for radii of curvature down to ~1.4cm.

¹W. Zhang, et al., Sci. Rep. 4, (2014)
²H. Sirringhaus et al., Science 290, 2123 (2000)
³S. Das et al., Nat. Nano. 3, 210 (2008)
⁴W. Yang et al., Appl. Phys. Lett. 96, 121107 (2010)
⁵F. Withers et al., Nano Lett. 14, 3987 (2014)