Inkjet Printed Circuits with 2D Semiconductor Inks for High‐Performance Electronics

Abstract

Air‐stable semiconducting inks suitable for complementary logic are key to create low‐power printed integrated circuits (ICs). High‐performance printable electronic inks with 2D materials have the potential to enable the next generation of high performance low‐cost printed digital electronics. Here, the authors demonstrate air‐stable, low voltage (<5 V) operation of inkjet‐printed n‐type molybdenum disulfide (MoS2), and p‐type indacenodithiophene‐co‐benzothiadiazole (IDT‐BT) field‐effect transistors (FETs), estimating an average switching time of τMoS2 ≈ 4.1 μs for the MoS2 FETs. They achieve this by engineering high‐quality MoS2 and air‐stable IDT‐BT inks suitable for inkjet‐printing complementary pairs of n‐type MoS2 and p‐type IDT‐BT FETs. They then integrate MoS2 and IDT‐BT FETs to realize inkjet‐printed complementary logic inverters with a voltage gain |Av| ≈ 4 when in resistive load configuration and |Av| ≈ 1.4 in complementary configuration. These results represent a key enabling step towards ubiquitous long‐term stable, low‐cost printed digital ICs.

Charge transport mechanisms in inkjet-printed thin-film transistors based on two-dimensional materials

“…3f). We find that σ MS increases monotonically with V G , indicating ntype behaviour, an on-off ratio of ≈ 25 (maximum gateinduced modulation of ≈ 2500%), and a mobility of up to ≈ 10 −1 cm 2 V −1 s −1 , in line with our recent results [134]. Below T ∼300 K the response of σ MS to the dielectric gating proved weak and we consequently resorted to ionic gating to tune σ MS at low T by scanning V G in 0.125 V steps between 0 and +2 V. At each step, a waiting time of ∼10 min minimised the influence of diffusion dynamics of the ions inside the MoS 2 film.…”

“…3g), and µ FE,MS increasing from ∼0.049 to ∼0.072 cm 2 V −1 s −1 , for V G 1.37 V (filled blue circles). These values result in agreement with the µ FE,MS recently reported for inkjetprinted MoS 2 FETs [134]. The opposite T -dependencies exhibited by µ FE,MS above and below V G ≈1.37 V are obviously consistent with a crossover from hopping transport at low V G to a band-like one at high V G , similar to the behavior reported in disordered isolated MoS 2 flakes [35].…”

“…3b). A V G was applied via an Al electrode through a thin AlO x layer (see Methods), which has previously shown to improve the modulation of inkjet-printed MoS 2 FETs [134] compared to inkjet-printed MoS 2 devices gated through SiO 2 /Si stacks [85]. In the selected printed MoS 2 devices, a small droplet of DEME-TFSI ionic liquid was optionally drop-cast on the device channel and a gold side-gate electrode was used to apply V G as the ionic-gate voltage.…”

“…All E2D ink devices were produced by using 25 printing passes. In the printed MoS 2 devices, we submerge our devices in bis(trifluoromethane)sulfonimide (TFSI) in 1,2-dichloroethane at 100 °C for 1 h. The treatment is performed in a nitrogen glovebox to avoid exposing TFSI to moisture in ambient atmosphere [134,155]. The devices are then annealed at 400 °C for 1 h to remove any residual solvent.…”

A Universal Approach for Room‐Temperature Printing and Coating of 2D Materials

“…In conventional ink formulations, additives such as surfactants, binders, and rheology modifiers are used to address the aforementioned problems and process the 2D material suspensions into printable or coatable inks. [7][8][9][10] For instance, large concentrations of polymeric binders (e.g., 70 mg mL −1 cellulose acetate butyrate) are needed to increase the viscosity of graphene inks to a level that is suitable for screen printing. [11] Since typical additives adversely affect the electronic properties (e.g., Processing 2D materials into printable or coatable inks for the fabrication of functional devices has proven to be quite difficult.…”