Fully screen printed stretchable electrochromic displays

Abstract

The advent of the Internet of Things and the growing interest in continuous monitoring by wearables have created a need for conformable and stretchable displays. Electrochromic displays (ECDs) are receiving attention as a cost-effective solution for many simple applications. However, stretchable ECDs have yet to be produced in a robust, large scale and cost-efficient manner. Here we develop a process for making fully screen printed stretchable ECDs. By evaluating commercially available inks with respect to electromechanical properties, including electrochromic PEDOT:PSS inks, our process can be directly applied in the manufacturing of stretchable organic electronic devices. The manufactured ECDs retained colour contrast with useful switching times at static strains up to 50 % and strain cycling up to 30 % strain. To further demonstrate the applicability of the technology, double-digit 7-segment ECDs were produced, which could conform to curved surfaces and be mounted onto stretchable fabrics while remaining fully functional. Based on their simplicity, robustness and processability, we believe that low cost printed stretchable ECDs can be easily scaled up and will find many applications within the rapidly growing markets of wearable electronics and the Internet of Things.

Reflective and Complementary Transmissive All‐Printed Electrochromic Displays Based on Prussian Blue

“…Impedance spectroscopy (Figure S5, Supporting Information) was conducted using a potentiostat (Biologic SP‐200), which was connected to a lateral device comprising a layer of the printed transparent electrolyte bridging two printed carbon electrodes, as reported elsewhere. [ 6 ] The thickness of the printed electrolyte layer was assessed with an optical profilometer (Sensofar PLu neox 3D) and an evaluation unit for data acquisition (Heidenhain Evaluation Electronics ND287).…”

“…Due to their advantages, EC devices have also found use as smart labels for Internet of Things (IoT) and wearable electronics. [4][5][6][7] Extensive research has been performed in the field of electrochromics to enhance the color contrast or alter the color hue of the resultant EC device. Researchers have adjusted the architecture of the devices, chemically modified the individual EC materials, and introduced various performance-enhancing additives to achieve these goals.…”

Screen-Printed Corrosion-Resistant and Long-Term Stable Stretchable Electronics Based on AgAu Microflake Conductors

“…23 As the processing parameters of the ink can often be kept below 130 °C, soft and sensitive substrates can be used. 24 Silicone elastomers, such as PDMS, are often used in stretchable electronics due to their good mechanical properties and chemical stability. 19,25,26 However, their low surface energy and adhesion, together with contamination issues, make them less suitable for screen printing.…”

“…Screen printing can produce any two-dimensional (2D) pattern with resolutions down to 100 μm readily achievable, while resolutions down to 30–40 μm have been reported when specialized equipment, inks, and substrate parameters are adopted . As the processing parameters of the ink can often be kept below 130 °C, soft and sensitive substrates can be used . Silicone elastomers, such as PDMS, are often used in stretchable electronics due to their good mechanical properties and chemical stability. ,, However, their low surface energy and adhesion, together with contamination issues, make them less suitable for screen printing. , Instead, some of the most commonly and successfully employed elastic substrates for screen printing are polyurethanes (PU) and thermoplastic polyurethane variants (TPU) due to their good elasticity, stability, and higher surface energy, which facilitates additive manufacturing. , The properties of the elastic matrix of a stretchable screen printing ink are of equal importance, as the ink needs similarly high surface energy as the substrate to adhere well and avoid delamination and cracking during deformation.…”

Intrinsically Stretchable Organic Electrochemical Transistors with Rigid‐Device‐Benchmarkable Performance

“…The on/off ratio and mobility of stretchable OECTs are essential parameters for evaluating their frequency response and switching properties for emerging soft bioelectronic applications such as stretchable neuroelectronic computing [ 32 ] and stretchable display. [ 33 ] Therefore, in the past years, intensive efforts have been dedicated to resolving these problems, including using a buffer layer between the substrate and channel [ 25 ] and using different substrates. [ 34 ] However, limited progress was made, and the underlying reasons remain unclear.…”