A combination of semi-metallic graphene and photosensitive two-dimensional (2D) transition metal dichalcogenide for heterostructures is ideal for high-performance optoelectronic device applications. Here, we first report semitransparent/flexible photodetectors (PDs) employing trifluoromethanesulfonyl-amide (TFSA)-doped graphene (GR) (TFSA-GR)/WS2 vertical heterostructures. The TFSA-GR/WS2 PDs show a delta-function-like photo-/dark-current (or on/off) ratio-vs-voltage behavior at zero bias, irrespective of wavelength (λ), meaning “self-powered”, mainly resulting from the surface doping of GR. The photoresponse is very sensitive in a wide ultraviolet-to-visible λ range. Maximum key figures of merit obtained for the PDs: responsivity (R), external quantum efficiency, and detectivity are 0.14 AW?1, 40%, and 2.5 × 109 cm Hz1/2 W?1, respectively, comparable to or even larger than those of previously-reported self-powered and/or hetero-structured PDs. The average transmittance of the PDs in the visible region is about 40%, indicating their semitransparency. The PDs maintain 88% of the initial R even after bending tests at 4 mm bending radius for 3000 cycles, demonstrating the excellent flexibility.
Department of Applied Physics Institute of Natural Sciences and Integrated Education Institute for Frontier Science and Technology (BK21 Four) Kyung Hee University
NSTL
Elsevier
