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Department of Chemistry
Physical chemistry of polymer enhanced materials for advanced electro-optics
Dr. rer. nat. Alexander Lorenz
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Research Topics

Opto-optic / Photoresponsive Devices And Hybrid Materials

Thin LC film can effectively manipulated with focused laser light in hybridized samples with photovoltaic fields.

Please see our latest work:

Open Access: A. Habibpourmoghadam, L. Lucchetti, D. R. Evans, V. Y. Reshetnyak, A. Lorenz, Laser-induced erasable patterns in a N* liquid crystal on an iron doped lithium niobate surface, Optics Express 25, 26148 (2017).

Invited paper: A. Habibpourmoghadam, L. Jiao, F. Omairat, D. R. Evans, V. Y. Reshetnyak, A. Lorenz, Confined photovoltaic fields in a photo-responsive liquid crystal test cell, Liquid Crystals XXI, Proceedings Volume 10361, 1036112 (2017).

A. Habibpourmoghadam, L. Jiao, V. Reshetnyak, D. R. Evans, A. Lorenz, Optical manipulation and defect creation in a liquid crystal on a photo responsive surface, Physical Review E 96, 022701 (2017). 


(optical manipulation / non-linear opts-optical responses)

Also: Towards advanced strategies for the enhancement of LC electro-optics via photo generated polymer

Polymer Enhanced Nematic Liquid Crystals

Nematic liquid crystals can show continuous phase modulation properties and surprisingly fast response times (well below 2 ms) if doped with a tailored mixture of insitu generated copolymer. Mixture composition and curing conditions are challenging research topics with a potential to push smart windows technology, displays and also bistable devices. 

See: A. Lorenz, L. Braun, V. Kolosova, "Continuous Optical Phase Modulation in a Copolymer Network Nematic Liquid Crystal." ACS Photonics 3, 1188 (2016).


Soft Responsive Materials With Induced Chirality

Fast electro-optic modulations with sub millisecond response times can be achieved in chiral nematic LCs (flexoelectro-optic responses) or blue phase LCs (Kerr-effect type responses). Here, chirality is usually induced in an otherwise non-chiral host LC. 

These advanced electro-optical materials have a huge potential to complement and even replace today's LC technologies. Anyway, many challenges still need to be addressed. Therefore, we have developed fitted experimental techniques to investigate their properties quantitatively, so we can go ahead and improve their properties!

One example, where we investigated how added polymer improved the response properties of hyper twisted chiral nematic LCs can be found here:

A. Lorenz, D. J. Gardiner, S. M. Morris, F. Castles, M. M. Qasim, S. S. Choi, W.-S. Kim, H. J. Coles, T. D. Wilkinson "Electrical addressing of polymer stabilized hyper-twisted chiral nematic liquid crystals with interdigitated electrodes: Experiment and model," Appl. Phys. Lett. 104, 071102 (2014).

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Dr. Alexander Lorenz

Physical Chemistry

Principal investigator, DFG grant 1922/4-1 'Photoactive LC Nanodispersions'

Alexander Lorenz
+49 5251 60-5728
+49 5251 60-4208
NW 1 872

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