Materials 2016, 9(4), 250; https://doi.org/10.3390/ma9040250
Forming Spacers in Situ by Photolithography to Mechanically Stabilize Electrofluidic-Based Switchable Optical Elements
Meihong Wang 1,†, Yuanyuan Guo 1,†, Robert A. Hayes 1,3,*
, Danqing Liu 2, Dirk J. Broer 2 and Guofu Zhou 1,3,4
, Danqing Liu 2, Dirk J. Broer 2 and Guofu Zhou 1,3,41
Electronic Paper Display Institute, South China Normal University, Higher Education Mega Center, Guangzhou 510006, China
2
Eindhoven University of Technology, Institute for Complex Molecular Systems, Eindhoven 5612AP, The Netherlands
3
Shenzhen Guohua Optoelectronics Tech. Co. Ltd., Shenzhen 518110, China
4
Academy of Shenzhen Guohua Optoelectronics, Shenzhen 518110, China
†
These authors contributed equally to this work.
*
Author to whom correspondence should be addressed.
Academic Editor: Roberta Bongiovanni
Received: 23 February 2016 / Revised: 12 March 2016 / Accepted: 24 March 2016 / Published: 30 March 2016
(This article belongs to the Special Issue Materials for Photolithography and 3D Printing)
Abstract
Electro-Fluidic Displays (EFD) have been demonstrated to be an attractive technology for incorporation into portable display devices. EFDs have excellent optical efficiency and fast switching enabling video content. Ensuring mechanical stability of EFD display cells is a key challenge and essential for developing large area as well as flexible displays. Although the electro-optic performance of an EFD, unlike a liquid crystal display (LCD), is insensitive to cell-gap, extreme changes in cell-gap can result in irreversible collapse of the cell. Here we use photolithography to develop spacers to prevent cell-gap collapse and provide the required mechanical stability for EFD devices. The spacer is formed directly on the cover plates (ITO/glass) after cell assembly with UV light induced phase separation polymerization in the illuminated area. Phase separation behavior between polar aqueous solution and polymer is closely related to the solubility of acrylate monomers. In this work, polyethylene glycol diacrylate (PEGDA) as cross-linker, 2-hydroxyethyl acrylate (HEA) and acrylic acid or acrylamide as co-monomers are investigated for fabricating the spacers. PEGDA was added to the mixtures in order to increase the mechanical strength of the spacer. The spacers showed excellent performance for cell-gap control in EFD devices. View Full-TextKeywords:
electrofluidic display; electrowetting; spacer; phase separation; photopolymerization; mechanical stability
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Wang, M.; Guo, Y.; Hayes, R.A.; Liu, D.; Broer, D.J.; Zhou, G. Forming Spacers in Situ by Photolithography to Mechanically Stabilize Electrofluidic-Based Switchable Optical Elements. Materials 2016, 9, 250.
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