Patterning of liquid crystals using soft-imprint replication of surface alignment patterns
Soft-imprint alignment processes for patterning liquid crystal polymer layers via contact with a reusable alignment template are described herein. An example soft-imprint alignment process includes contacting a liquid crystal polymer layer with a reusable alignment template that has a desired surface alignment pattern such that the liquid crystal molecules of the liquid crystal polymer are aligned to the surface alignment pattern via chemical, steric, or other intermolecular interaction. The patterned liquid crystal polymer layer may then be polymerized and separated from the reusable alignment template. The process can be repeated many times. The reusable alignment template may include a photo-alignment layer that does not comprise surface relief structures that correspond to the surface alignment pattern and a release layer above this photo-alignment layer. A reusable alignment template and methods of fabricating the same are also disclosed.
1. A reusable alignment template for use in a liquid crystal soft-imprint alignment process, the reusable alignment template comprising;
a substrate; and
a photo-alignment layer overlying the substrate, and a release layer overlying the photo-alignment layer, the photo-alignment layer comprising a surface alignment pattern,
wherein the surface alignment pattern of the photo-alignment layer does not comprise surface relief structures,
wherein the release layer comprises fluorosilane or polydimethylsiloxane (PDMS), and
wherein the photo-alignment layer comprises photoresist;
wherein the release layer is configured to provide for reuse of the reusable alignment template.
2. The reusable alignment template of claim 1 , further comprising a liquid crystal polymer layer disposed between the photo-alignment layer and the release layer.
3. The reusable alignment template of claim 1 , wherein the surface alignment pattern comprises Pancharatnam-Berry phase effect (PBPE) features.
4. The reusable alignment template of claim 3 , wherein the PBPE features comprise a diffraction grating pattern.
5. The reusable alignment template of claim 1 , wherein the surface alignment pattern comprises an inverse of Pancharatnam-Berry phase effect (PBPE) features.
6. The reusable alignment template of claim 1 , wherein said photo-alignment layer is optically transmissive.
7. The reusable alignment template of claim 1 , wherein said substrate is optically transmissive.
8. The reusable alignment template of claim 1 , wherein said release layer has a thickness of less than about 10 nm.
9. The reusable alignment template of claim 1 , wherein said photo-alignment layer has a thickness of about 10 nm to about 300 nm.
10. The reusable alignment template of claim 1 , wherein said substrate comprises a material selected from the group consisting of glass, quartz, sapphire, indium tin oxide (ITO), a polymeric material, and combinations thereof.
11. A process for fabricating a reusable alignment template for use in a liquid crystal soft-imprint alignment process, the process comprising:
depositing a photo-alignment layer on a surface of a substrate;
photo-patterning the photo-alignment layer to form a desired surface alignment pattern therein;
depositing a release layer over the photo-patterned photo-alignment layer; and
using said template multiple times to align different liquid crystal layers,
wherein the surface alignment pattern of the photo-alignment layer does not comprise surface relief structures,
wherein the release layer comprises fluorosilane or polydimethylsiloxane (PDMS),
wherein the photo-alignment layer comprises photoresist; and
wherein the release layer is configured to provide for reuse of the reusable alignment template.
12. The process of claim 11 , further comprising depositing a liquid crystal polymer layer on the photo-patterned photo-alignment layer prior to depositing the release layer over the photo-patterned photo-alignment layer.
13. The process of claim 12 , wherein depositing the liquid crystal polymer layer comprises jet depositing the liquid crystal polymer layer.
14. The process of claim 12 , wherein depositing the liquid crystal polymer layer comprises spin-coating the liquid crystal polymer layer.
15. The process of claim 12 , wherein said photo-alignment layer is optically transmissive or transparent.
16. The process of claim 13 , wherein the liquid crystal polymer layer is polymerized by passing light through said photo-alignment layer.
17. The process of claim 11 , wherein the surface alignment pattern comprises Pancharatnam-Berry phase effect (PBPE) features.
18. The process of claim 17 , wherein the PBPE features comprise a diffraction grating pattern.
19. The process of claim 11 , wherein the surface alignment pattern comprises an inverse of Pancharatnam-Berry phase effect (PBPE) features.