Encapsulation of Screen-Printed Electrolyte-Based Organic Electronic Components for Long-Term Operation in Varying...

With the advancement of printing techniques, material choices, and ink development, high-performance printed electrochemical components relying on organic conducting polymers are beginning to mature and find traction in numerous applications in different areas, such as organic electrochromic displays (OECDs) and logic circuits based on organic electrochemical transistors (OECTs). However, the inherent hygroscopic nature of various materials in the devices, combined with electrochemically dictated working mechanisms, makes the devices sensitive to environmental changes, such as relative humidity (RH) levels and temperature (T). To ensure reliable operation of the devices, there is a need to mitigate the influence of ambience. In this article, we use commercially available printable adhesives and plastic substrates with predeposited barrier coatings to provide device encapsulation. The developed process allows for tight and conformal sealing along the topography of printed conductors reaching out from the encapsulated devices, thereby blocking the most probable leakage path. Consequently, the device performance with respect to environmental fluctuations is maintained, and the best barrier materials ensure that the performances of screen-printed OECDs and OECTs remain intact after storage in harsh conditions, such as the combination of low RH and low T or high RH and high T. Satisfactory results are achieved after a storage time of 1 week in each condition; 10% RH and 10 °C, 80% RH and 20 °C, and 90% RH and 40 °C. Additional tests performed for even longer storage times and harsh conditions, 90% RH and 40 °C, and extremely dry environment (<3% RH and 20 °C), respectively, showed devices with excellent switching performances upon evaluation. It was also discovered that the color retention of OECDs switched to their colored state, after 1 week of storage in open-circuit mode at different environmental conditions, was considerably improved upon encapsulation with barrier films.