Photonic Landscape Engineering for Tailor-Made Coherent Emission from Strongly-Coupled Organic and Biological Fluorophores
Final Report Abstract
Strong coupling between light and matter describes a coherent interaction of a material with photons in a resonator, resulting in a new kind of quasiparticle, the polariton. Within this project we have investigated how particular organic and biologically produced fluorescent dyes interact with a microcavity – a wavelength-scale resonator between two mirrors. The aim of the project was to systematically screen available organic dyes such as Phthalocyanines, nanomaterials such as carbon nanotubes and biologically produced fluorophores such as green fluorescent protein (GFP) for their suitability to enable such strong coupling. Furthermore, the geometry of the resonator plays a critical role in strong coupling and light emission from such systems. We studied the influence of lateral patterning of the cavity mirrors on the properties of so called polariton lasers – systems that enable a laser-like condensation of polaritons. The results of this project can be grouped into three categories: (i) fundamental investigation of material properties towards strong coupling, (ii) the influence of resonator structure on the behaviour and performance of polariton lasers and (iii) the application of strong light matter coupling for photonic devices. Within (i), we have investigated a large number of materials for strong coupling, including Phthalocyanines such as SubPc and SubNc, Coumarines such as C545T, nanomaterials such as single walled carbon nanotubes (SWNTs) and biologically produced materials such as GFP and mScarlet. We were thus able to create a database of strong coupling materials over the whole visible range and into the near-infrared. Particular materials showed great potential for different applications due to their unique combination of light-matter interaction- (or oscillator-) strength, luminescence quantum efficiencies and particular fabrication methods, which we explored in detail. The resonator microstructure can have a significant influence on the emission properties of microcavities, their ability to show strong coupling, as well as their performance. Through (ii), we were able to introduce lateral patterning with periodic structures into the vertical microcavities by an etch-and-overgrowth technique. Using either the organic material system Alq3:DCM or GFP as active material, we fabricated photon and polariton laser systems utilising such lateral patterning to influence the emission properties such as the directionality of the devices. By introducing periodic structures and selective defects in them, we can tune the emission from being very directional to encompassing a more wide-angle range. We were also able to show that such defects can directly improve the device performance, increasing emission intensity and decreasing the nonlinear thresholds in the system through concentration of light. The initial results showed a large potential for novel applications of strong coupling in photonic devices. In (iii), we were able to realise a multitude of scenarios. For the first time, we showcased the influence of strong coupling in organic solar cells in great detail. By utilising the strong absorbers SubNc and SubPc in a microcavity-based solar cell, we could directly influence the band gap of said active materials. In turn, we were able to demonstrate a reduced energy loss from absorbed photon energy to extracted voltage and showcase a concrete benefit strong coupling can have for photovoltaics. The ability to influence the band gap of materials was further explored in SWNT-based photodetectors. By changing resonator thickness and thus red-shifting to resulting polaritons we could realise spectroscopic narrowband photodetectors in the near infrared, an increasingly desirable spectral range. Finally, we were able to demonstrate a first, efficient, polariton-based OLED through a particular design where an additional absorber material is introduced in a light-emitting device. These polariton OLEDs show an increase of efficiency of at least an order of magnitude over previous designs and exhibit the potential for bright, spectrally narrowband and angle-independent emission, crucial for high fidelity displays.
Publications
- “Narrowband Organic Light‐Emitting Diodes for Fluorescence Microscopy and Calcium Imaging”, Advanced Materials 31, 1903599, (2019)
Caroline Murawski, Andreas Mischok, Jonathan Booth, Jothi Dinesh Kumar, Emily Archer, Laura Tropf, Chang‐Min Keum, Ya‐Li Deng, Kou Yoshida, Ifor DW Samuel, Marcel Schubert, Stefan R Pulver, and Malte C Gather
(See online at https://doi.org/10.1002/adma.201903599) - “Strong light-matter coupling for reduced photon energy losses in organic photovoltaics”, Nature Communications 10(1), 3706, (2019)
Vasileios C Nikolis, Andreas Mischok, Bernhard Siegmund, Jonas Kublitski, Xiangkun Jia, Johannes Benduhn, Ulrich Hörmann, Dieter Neher, Malte C Gather, Donato Spoltore, and Koen Vandewal
(See online at https://doi.org/10.1038/s41467-019-11717-5) - “A substrateless, flexible, and water-resistant organic light-emitting diode”, Nature Communications 11, 6250, (2020)
Changmin Keum, Caroline Murawski, Emily Archer, Seonil Kwon, Andreas Mischok, and Malte C Gather
(See online at https://doi.org/10.1038/s41467-020-20016-3) - “Defect-state lasing in photonic lattices of metal-organic microcavities”, Advanced Photonics Research 2, 2000116, (2020)
Mona Kliem, Thomas Kiel, Andreas Mischok, Stefan Meister, Hartmut Fröb, Kurt Busch, and Karl Leo
(See online at https://doi.org/10.1002/adpr.202000116) - “Spectroscopic near-infrared photodetectors enabled by strong light-matter coupling in single walled carbon nanotubes”, Journal of Chemical Physics 153, 201104
Andreas Mischok, Jan Lüttgens, Felix Berger, Francisco Tenopala-Carmona, Seonil Kwon, Caroline Murawski, Bernhard Siegmund, Jana Zaumseil, and Malte C Gather
(See online at https://doi.org/10.1063/5.0031293) - “Effective permittivity of co-evaporated metal-organic mixed films”, Journal of Applied Physics 129, 083101, (2021)
Andreas Mischok, Nathan Hale, Malte C Gather, and Andrea di Falco
(See online at https://doi.org/10.1063/5.0038899)
