Fully screen printed stretchable electrochromic displays

Ioannis Petsagkourakis,Ulrika Linderhed,Peter Andersson Ersman,Klas Tybrandt,Valerio Beni

doi:10.1088/2058-8585/ac3eb2

Ioannis Petsagkourakis, Ulrika Linderhed + Show 3 more

Open Access

https://doi.org/10.1088/2058-8585/ac3eb2

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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.

Highlights

Wearable and conformable technology has gained traction in recent years towards the long term goal of developing more affordable, interactive, and personalized devices [1, 2]
We evaluate a selection of commercial functional screen printing inks with respect to stretchability and observe a large variation in electromechanical characteristics of the PEDOT:PSS inks
The printed electrolyte strip used for these tests was in contact with printed PEDOT:PSS electrode pads at the ends, on top of which carbon contacts had been printed

Summary

Introduction

Wearable and conformable technology has gained traction in recent years towards the long term goal of developing more affordable, interactive, and personalized devices [1, 2]. The importance of lowering the cost of ECD manufacturing was recognized many years ago as a key to make this technology a viable alternative, or complement, to traditional displays [35] For this reason, printing techniques such as ink-jet and screen printing are frequently applied, as they offer unique advantages with respect to processing cost, throughput, and low material waste [34, 36, 37]. Manufacturing of ECDs by printing technologies can be performed onto a wide range of substrates, owing to the relatively low processing temperatures These include conventional plastic substrates (PET and Kapton) and sensitive materials, such as flexible, stretchable and soft substrates that often have low melting points, e.g. thermoplastic polyurethane (TPU). The ECDs remain functional up to 100% single strain and upon cycling up to 30% strain, the switching time increases with strain

Experimental section

Results and discussion

Conclusions