The design, fabrication, and characterization of ultra-high responsivity photodetectors based on mesoscopic multilayer MoS2 is presented, which is a less explored system compared to direct band gap monolayer MoS2 that has received increasing attention in recent years. The device architecture is comprised of a metal-semiconductor-metal (MSM) photodetector, where Mo was used as the contact metal to suspended MoS2 membranes. The photoresponsivity was measured to be ~1.4 × 104 A/W, which is > 104 times higher compared to prior reports, while the detectivity D* was computed to be ~2.3 × 1011 Jones at 300 K at an optical power P of ~14.5 pW and wavelength λ of ~700 nm. In addition, the dominant photocurrent mechanism was determined to be the photoconductive effect (PCE), while a contribution from the photogating effect was also noted from trap-states that yielded a wide spectral photoresponse from UV-to-IR (400 nm to 1100 nm) with an external quantum efficiency (EQE) ~104. From time-resolved photocurrent measurements, a decay time τd ~ 2.5 ms at 300 K was measured from the falling edge of the photogenerated waveform after irradiating the device with a stream of incoming ON/OFF white light pulses.

The hybrid structure of zero-dimensional (0D) graphene quantum dots (GQDs) and semiconducting two-dimensional (2D) MoS2 has been investigated, which exhibit outstanding properties for optoelectronic devices surpassing the limitations of MoS2 photodetectors where the GQDs extend the optical absorption into the near-UV regime. The GQDs and MoS2 films are characterized by Raman and photoluminescence (PL) spectroscopies, along with atomic force microscopy. After outlining the fabrication of our 0D–2D heterostructure photodetectors comprising GQDs with bulk MoS2 sheets, their photoresponse to the incoming radiation was measured. The hybrid GQD/MoS2 heterostructure photodetector exhibits a high photoresponsivity R of more than 1200 A W–1 at 0.64 mW/cm2 at room temperature T. The T-dependent optoelectronic measurements revealed a peak R of ∼544 A W–1 at 245 K, examined from 5.4 K up to 305 K with an incoming white light power density of 3.2 mW/cm2. A tunable laser revealed the photocurrent to be maximal at lower wavelengths in the near ultraviolet (UV) over the 400–1100 nm spectral range, where the R of the hybrid GQDs/MoS2 was ∼775 A W–1, while a value of 2.33 × 1012 Jones was computed for the detectivity D* at 400 nm. The external quantum efficiency was measured to be ∼99.8% at 650 nm, which increased to 241% when the wavelength of the incoming laser was reduced to 400 nm. Time-resolved measurements of the photocurrent for the hybrid devices resulted in a rise time τrise and a fall time τfall of ∼7 and ∼25 ms, respectively, at room T, which are 10× lower compared to previous reports. From our promising results, we conclude that the GQDs exhibit a sizable band gap upon optical excitation, where photocarriers are injected into the MoS2 films, endowing the hybrids with long carrier lifetimes to enable efficient light absorption beyond the visible and into the near-UV regime. The GQD–MoS2 structure is thus an enabling platform for high-performance photodetectors, optoelectronic circuits, and quantum devices.

Terpineol leads to effective exfoliation and excitonic enhancement in solution dispersions of MoS2 and WS2, which also yields enhancement in electronic transport properties. Such dispersions are amenable to high-performance electronic and opto-electronic devices using manufacturable routes.

Continuous miniaturization of devices, for example in consumer electronics, defense and aerospace applications, is largely driven by our desire for smaller, light-weight, ultra-thin devices, where such structures on fully flexible platforms can drive down costs even further [1,2]. For flexible electronics applications in particular, the substrates pose less restrictions compared to the Si-based semiconductor industry, where in the former, a wide variety of additive manufacturing techniques easily lend themselves for the production of functional structures on arbitrary substrates within the context of what is generally referred to as 'printed electronics.' Examples of functional printed structures include printed batteries, solar cells, light emitting diodes that have been formed using organic and inorganic materials [3,4]. One commonly used additive manufacturing technique for printed electronics is ink-jet printing, which allows for a fast and cheap approach for patterning electronic devices, circuits and systems using a range of inks [5], from metallic to semiconducting, to construct active or passive structures [6].With the advent of two-dimensional (2D) layered materials (LMs), which includes quintessential 2D graphene, solution dispersions of 2DLMs have been formulated recently for ink-jet printing [7][8][9][10]. Although great progress has been made to produce liquid dispersions of 2DLMs, challenges still lie in the reliable mass production of these materials for practical applications. Some of the techniques used for solution-based exfoliation include intercalant assisted exfoliation [11,12], thermal shock [13], or shear oxidation of graphite [14] although the oxidation process results in structural defects and dispersions that are often