Intense pulsed light (IPL) annealing of graphene inks is demonstrated for rapid post-processing of inkjet-printed patterns on various substrates. A conductivity of ≈25,000 S m(-1) is achieved following a single printing pass using a concentrated ink containing 20 mg mL(-1) graphene, establishing this strategy as a practical and effective approach for the versatile and high-performance integration of graphene in printed and flexible electronics.

Wearable and skin electronics benefit from mechanically soft and stretchable materials to conform to curved and dynamic surfaces, thereby enabling seamless integration with the human body. However, such materials are challenging to process using traditional microelectronics techniques. Here, stretchable transistor arrays are patterned exclusively from solution by inkjet printing of polymers and carbon nanotubes. The additive, non-contact and maskless nature of inkjet printing provides a simple, inexpensive and scalable route for stacking and patterning these chemically-sensitive materials over large areas. The transistors, which are stable at ambient conditions, display mobilities as high as 30 cm 2 V −1 s −1 and currents per channel width of 0.2 mA cm −1 at operation voltages as low as 1 V, owing to the ionic character of their printed gate dielectric. Furthermore, these transistors with double-layer capacitive dielectric can mimic the synaptic behavior of neurons, making them interesting for conformal brain-machine interfaces and other wearable bioelectronics.

Recent developments in liquid-phase processing of carbon nanomaterials have established graphene as a promising candidate for printed electronics. Of great importance in the ink formulation is the stabilizer, which has to provide excellent dispersion stability and tunability in the liquid state, and also decompose into chemical moieties that promote high electrical conductivity and robust mechanical and environmental stability. Here we demonstrate the promise of nitrocellulose as a synergistic polymer stabilizer for graphene inks. Graphene processed with nitrocellulose is formulated into inks with viscosities ranging over 4 orders of magnitude for compatibility with a wide range of deposition methods. Following thermal treatment, the graphene/nitrocellulose films offer high electrical conductivity of ∼40 000 S/m, along with mechanical flexibility. Moreover, in contrast to state-of-the-art graphene inks based on ethyl cellulose, the nitrocellulose residue offers superior mechanical and environmental stability as assessed by a suite of stress tests, including the Scotch tape test, a water sonication test, and an 85/85 damp heat test. By exploring the fundamental chemistry underlying these macroscopic benefits, we provide insight into binder selection for functional nanomaterial inks while producing a high-performance graphene ink with strong potential for printed and flexible electronics.

Figure 6. Dual-ion SPEs with specific design. a) SPE prepared by vertically aligned 2D sheets and its microstructure. Reproduced with permission. [92] Copyright 2019, Wiley. b) Illustration of sandwich-type composite electrolyte (SCE) combined "ceramic-in-polymer" (CIP) electrolyte and "polymer-inceramic"(PIC) electrolyte. Reproduced with permission.

SCs and MSCs has been hindered by several issues. In particular, the synthesis, postreaction treatment, and instability of GO present processing challenges for widespread application. [ 14,22 ] In addition, the complex fabrication required for GO-based electrodes limits the cost potential and versatility of devices, particularly for MSCs with interdigitated structures. [ 4,23 ] Chemical vapor deposition has also been used to prepare graphene directly, but has limited scalability and often requires harsh synthetic conditions. [24][25][26][27][28][29] Laser scribing was recently developed to prepare porous graphene networks from polyimide. [ 30,31 ] This technology simplifi es the fabrication processes of MSCs compared to the photolithography approach, but still suffers from several limitations, such as limited compatibility with other substrates beyond polyimide and low energy storage ability. [ 4 ] Inkjet printing offers a desirable suite of advantages, including additive, non-contact, digital fabrication with high spatial resolution. Moreover, inkjet printing is an industrially mature technology, facilitating rapid transfer of technology from prototyping to manufacturing. The process and substrate compatibility achieved by this method, along with its commercial relevance, make the fabrication of microsupercapacitors by inkjet printing highly advantageous. However, challenges remain in the development of suitable graphene-based inks combining process compatibility and desirable electrical performance. Consequently, the development of a facile and scalable method for the fabrication of graphene electrodes for high-performance SCs and MSCs remains an outstanding challenge.Recent reports have demonstrated liquid-phase exfoliation of graphite for the production of stable graphene dispersions using the polymer ethyl cellulose in common, low-cost solvents such as ethanol and terpineol. [32][33][34][35] The graphene/ethyl cellulose (G/EC) system is suitable for applications in scalable fl exible electronics, with demonstrated processing ease and compatibility with a range of desirable substrates, as well as excellent electrical conductivity and mechanical fl exibility. Moreover, this system can be tailored for a range of additive manufacturing technologies including inkjet, gravure, and screen printing. [ 32,36 ] Herein, we extend this promising processing platform to electrochemical energy storage applications, realizing high-performance solid-state SCs. The suitability of the G/EC material for all-solid-state SC applications is fi rst evaluated using blade-coated and spin-coated thin-fi lm electrodes in sandwich-structured devices. In this confi guration, the high-conductivity, binder-free electrode mitigates the need for a separate current collector, simplifying the device fabrication process and eliminating potentially weak interfaces to enable Advances in thin-fi lm energy storage technologies are required to power the emerging fi eld of printed and portable electronics, with applications spanning biomedical and en...