Inkjet-printed TMDC–graphene heterostructures for flexible and broadband photodetectors

Abstract

The development of inkjet-printed 2D crystal inks offers the ability to print different 2D materials on various substrates to form vertical heterostructures. However, the detailed characterization of the atomic structures of the inkjet-printed MoTe2 nanosheets has been rarely reported. In this work, water-based 2D crystal inks of MoTe2, WS2, and graphene have been prepared and printed to obtain the flexible photodetectors. The absorption coefficient of MoTe2 has been estimated as α (500 nm) = 925 ± 47 lg−1 m−1 using the gravimetric method. Intriguingly, the inkjet-printed MoTe2 nanosheets down to 4 nm show both the semiconducting 2H and metallic 1T′ phases. The responsivities of the photodetectors based on MoTe2/graphene and WS2/graphene heterostructures can reach 120 mA/W and 2.5 A/W at 532 nm, respectively. Moreover, the inkjet-printed MoTe2/graphene shows a responsivity of 7.7 mA/W at 940 nm. The fabrication technique of inkjet printing will help design flexible optoelectronic devices based transition metal dichalcogenide–graphene heterostructures for the near-infrared photo detection.

Two‐Dimensional Van Der Waals Thin Film and Device

“…Nevertheless, graphene with its high conductivity can serve as electrodes to accomplish a photodetector incorporating graphene/WS 2 /graphene vertical heterojunction structures using full printing techniques. [ 136 ]…”

“…Flexible photodetectors based on MoTe 2 /graphene and WS 2 /graphene heterostructures can be manufactured using inkjet printing systems, as illustrated in Figure 4d. [ 136 ] A photodetector featuring a molybdenum telluride (MoTe 2 )/graphene heterostructure has attained a responsivity of 120 mA W −1 , and a flexible device based on WS 2 /graphene has achieved a responsivity as high as 2.5 A W −1 ( V ds = 5 V; 532 nm) (Figure 4e,f).…”

“…d–f) Reproduced with permission. [ 136 ] Copyright 2022, AIP Publishing. g) Schematic diagram of a PEC system built for evaluating photoresponse behavior; three electrodes in our experiment were assembled at a fixed distance of 1 cm from each other.…”

“…Nevertheless, graphene with its high conductivity can serve as electrodes to accomplish a photodetector incorporating graphene/WS 2 /graphene vertical heterojunction structures using full printing techniques. [136] Semiconductor TMDCs' quantum condensation effects come into play as the layer thickness decreases, leading to a considerable light absorption between 1 and 2 eV. This is very interesting for light detection, as seen in gallium sulphide (GaS), gallium(II) selenide (GaSe), gallium telluride (GaTe), SnS 2 , InSe, and In 2 Se 3 .…”

“…f) Dependence of photocurrent and responsivity of a WS 2 /graphene heterostructure with respect to laser power at V ds of 5 V. Inset: typical photograph of the flexible photodetector. d-f) Reproduced with permission [136]. Copyright 2022, AIP Publishing.…”