Printed electronics is a novel microfabrication paradigm that is particularly well suited for fabrication of low-cost, large-area electronics on flexible substrates. Applications include flexible displays, solar cells, RFID tags or sensor networks. Gravure printing is a particularly promising printing technique because it combines high print speed with high resolution patterning. In this thesis, gravure printing for printed electronics is advanced on multiple levels. The gravure process is advanced in terms of tooling and understanding of printing physics as well as its application to substrate preparation and device fabrication.
Gravure printing is applied to transform paper into a viable substrate for printed electronics. Paper is very attractive for printed electronics because it is low-cost, biodegradable, lightweight and ubiquitous. However, printing of high-performance electronic devices onto paper has been limited by the large surface roughness and ink absorption of paper. This is overcome here by gravure printing a local smoothing layer and printed organic thin-film transistors (OTFTs) are demonstrated to exhibit performance on-par with device on plastic substrates.
If highly-scaled features are to be printed by gravure, traditional gravure roll making techniques are limited in terms of pattern definition and surface finish. Here, a novel fabrication process for gravure rolls is demonstrated utilizing silicon microfabrication. Sub-3μm features are printed at 1m/s. Proximity effects are demonstrated for more complex highly-scaled features. The fluid mechanics of this effect is studied and it is suggested how it can be used to enhance feature quality by employing assist features.
Finally, advancements are made to printed organic thin-film transistors as an important technology driver and demonstrator for printed electronics. First, a novel scanned thermal annealing technique is presented that significantly improves the crystallization of an organic semiconductor and electrical performance. Second, transistors are fully gravure printed at a high print speed of 1m/s. By scaling both lateral and thickness dimensions and optimizing the printing processes, good electrical performance, low-voltage operation and low variability is demonstrated.
Title
Gravure-printed electronics: Devices, technology development and design
Published
2017-05-01
Full Collection Name
Electrical Engineering & Computer Sciences Technical Reports
Other Identifiers
EECS-2017-17
Type
Text
Extent
158 p
Archive
The Engineering Library
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