Abstract
In this work, we investigated the use of in-line linear electron beam irradiation (LEB) surface treatment integrated into a commercially compatible roll-to-roll (R2R) processing line, as a single fluorocarbon cleaning step, following flexography oil masking used to pattern layers for devices. Thermoelectric generators (TEGs) were selected as the flexible electronic device demonstrator; a green renewable energy harvester ideal for powering wearable technologies. BiTe/BiSbTe-based flexible TEGs (f-TEGs) were fabricated using in-line oil patterned aluminium electrodes, followed by a 600 W LEB cleaning step, in which the duration was optimised. A BiTe/BiSbTe f-TEG using an oil-patterned electrode and a 15 min LEB clean (to remove oil prior to BiTe/BiSbTe deposition) showed similar Seebeck and output power (S ~ 0.19 mV K−1 and p = 0.02 nW at ΔT = 20 K) compared to that of an oil-free reference f-TEG, demonstrating the success of using the LEB as a cleaning step to prevent any remaining oil interfering with the subsequent active material deposition. Device lifetimes were investigated, with electrode/thermoelectric interface degradation attributed to an aluminium/fluorine reaction, originating from the fluorine-rich masking oil. A BiTe/GeTe f-TEG using an oil-patterned/LEB clean, exceeded the lifetime of the comparable BiTe/BiSbTe f-TEG, highlighting the importance of deposited material reactivities with the additives from the masking oil, in this case fluorine. This work therefore demonstrates (i) full device architectures within a R2R system using vacuum flexography oil patterned electrodes; (ii) an enabling Electron beam cleansing step for removal of oil remnants; and (iii) that careful selection of masking oils is needed for the materials used when flexographic patterning during R2R.
Highlights
Thermoelectric generators (TEGs) exploit the voltage differential across n- and p-type materials when a temperature gradient is present, via the Seebeck effect, allowing for current to be driven through an applied electric load
This paper proposes a novel approach to overcome this challenge by incorporating a linear electron beam (LEB) process into the Physical vapour deposition (PVD)-R2R flexography process line
Al electrodes were deposited by selective vacuum metallization using a single-pass, 25 m min−1, R2R patterning based on flexographic printing of Krytox® 1506 oil as a mask during continuous circuit manufacture
Summary
Thermoelectric generators (TEGs) exploit the voltage differential across n- and p-type materials when a temperature gradient is present, via the Seebeck effect, allowing for current to be driven through an applied electric load. Roll-to-roll (R2R) is a desirable manufacturing technique for flexible electronics that can be utilised for devices such as f-TEGs. Webs of flexible substrates are wound at high speeds, e.g., 10–500 m min−1 from one roll, through processing chambers, back onto another roll. Physical vapour deposition (PVD) techniques, such as sputtering and thermal evaporation, offer high-quality and tuneable thin films and recently demonstrated promising R2R compatibility for high-throughput manufacturing of f-TEGs. To create patterned devices, flexography is an ideal PVD-R2R compatible process, offering high speeds (e.g., up to 180 m min−1), and relatively low set-up costs compared to that of traditional ink-jet or gravure techniques [4,9]
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
