Researchers develop a new photonic system based on perovskites and liquid crystals

Scientists from the University of Warsaw, Poland-based Military University of Technology, CNR Nanotec, the University of Southampton and the University of Iceland have designed a new photonic system with electrically tuned topological features, constructed of perovskites and liquid crystals. The new system can be used to create efficient light sources.

Perovskites are highly-studied materials that have the potential to revolutionize the solar energy fields, among others. These are durable and easy-to-produce materials, the special property of which is a high solar light absorption coefficient and they are therefore used to develop new, more efficient photovoltaic cells. In recent years, the emission properties of these materials, so far underestimated, have been used.

"We noticed that two-dimensional perovskites are very stable at room temperature, have high exciton binding energy and high quantum efficiency", said PhD student Karolina Lempicka-Mirek from the Faculty of Physics at the University of Warsaw, the first author of the publication. The team explained that these special properties can be used in the construction of efficient and unconventional light sources. 

Scientists managed to create a system in which excitons in a two-dimensional perovskite were strongly coupled with photons trapped in a birefringent photonic structure: a two-dimensional optical cavity filled with a liquid crystal. "In such a regime, new quasiparticles are created: excitonic polaritons, which are known primarily for the possibility of phase transition to non-equilibrium Bose-Einstein condensate, the formation of superfluid states at room temperature and strong light emission similar to laser light", explains University of Warsaw's Barbara Pietka.

"Our system turned out to be an ideal platform for creating photonic energy bands with non-zero Berry curvature and studying optical spin-orbit effects mimicking those previously observed in semiconductor physics at cryogenic temperatures", added Mateusz Krol, PhD student from the Faculty of Physics at the University of Warsaw. "In this case, we recreated the Rashba-Dresselhaus spin-orbit coupling in the strong light-matter coupling regime at room temperature".

"The generation of a polariton band with a non-zero Berry curvature was possible thanks to designing a special twist of the liquid crystal molecules at the surface of the mirrors", explains the co-author of the study, Wiktor Piecek from the Military University of Technology, where the tested optical cavities were fabricated.

The new work interfaces spinoptronic devices with electronics by combining electrical control over both the strong light-matter coupling conditions and artificial gauge fields.

Posted: Oct 16,2022 by Roni Peleg