Hybrid organic-inorganic semiconductor polariton condensates and transistors

• Applicant: Professor Dr. Sven Höfling
• Subject Area: Experimental Condensed Matter Physics
• Term: from 2020 to 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 429901270

Interaction of light with matter in semiconductors is central to our technology-driven world. When a semiconductor emits or absorbs light, a discrete event of energy exchange between a photon and an electron occurs. Instead of such discrete ‘jumps’ however, it is now possible to create optical and electronic systems in which photons and excited-state electrons are mixed together in an optical microcavity and energy is exchanged between them coherently, forming entirely new particles called ‘polaritons’. When a sufficient number of polaritons is generated in a cavity, they form a coherent state called a polariton condensate. Such condensates are a form of ‘liquid light’ and display quantum properties, even though the condensate can be quite large (tens of microns in diameter). These exotic objects are not simply an academic curiosity: they can be used as the basis for an entirely new type of electronics, called ‘polaritonics’. The ease of creating polariton condensates through optical pumping has recently led to demonstrations of numerous prototype polaritonic devices including low threshold lasers, interferometers, and transistors. The latter are almost entirely based on III-V semiconductors that offer superior material quality, despite being mainly restricted to low-temperature operation due to small exciton binding energies in such materials. Organic microcavities, owing to their very robust excitons, are much more resilient and are shown to support room-temperature polariton condensates, whilst suffering from the lack of efficient electrical injection. The state-of-the-art in both the fields of organic and inorganic polaritonics has now reached the maturity, wherein hybridization of the two classes of semiconductor materials in optical microcavities promises a whole gamut of new physics and potential devices.In the pioneering work by Agranovich et al., it was shown that hybrid organic-inorganic structures mixing two degenerate excitonic species – namely, Frenkel excitons and Wannier-Mott excitons – can combine many desirable properties, such as large exciton Bohr radii favoring polariton-polariton interaction and large oscillator strengths allowing operation at room temperature and deliver giant optical non-linearities. In the proposed project, we will explore the new fundamental physics of polaritons in hybrid microcavities containing both inorganic and organic semiconductors and aim at developing an entirely new generation of hybrid polaritonic systems that harness the benefits of hybridization. To address the challenges of this research, we propose an exceptionally strong academic partnership in the field of polaritonics between Germany and the Russian Federation. The consortium brings together the critical mass, complementary expertise, and unmatched experimental facilities necessary to ignite the new field of hybrid polaritonics and deliver ground-breaking results in the rapidly developing areas of quantum and photonic engineering.

• DFG Programme: Research Grants
• International Connection: Russia
• Partner Organisation: Russian Foundation for Basic Research
• Cooperation Partner: Professor Dr. Pavlos Lagoudakis