Electrically tunable organic-inorganic hybrid polaritons with monolayer WS2

We demonstrate the formation of hybrid organic-inorganic polaritons created through the simultaneous coupling of a J-aggregate dye and a CVD grown tungsten-disulphide monolayer to a confined optical microcavity mode.... [ view full abstract ]

We demonstrate the formation of hybrid organic-inorganic polaritons created through the simultaneous coupling of a J-aggregate dye and a CVD grown tungsten-disulphide monolayer to a confined optical microcavity mode. Electrical tuning of the tungsten-disulphide exciton energy results in a controllable change in the relative mixing of Frenkel and Wannier-Mott excitons within the polariton states. Transition metal dichalcogenides (TMDs), such as MoSe2 and WS2, have received increased attention due to the ability to produce large, atomically flat monolayer domains with intriguing optical properties [1] (see Fig. 1a). Whilst exfoliated material has generally shown lower defect densities, the level of control achieved in CVD offers strong potential for the fabrication of device structures. The large exciton-binding energy and direct band gap typical for these monolayers leads to stable exciton formation at room temperature, narrow absorption and emission peaks. These properties make TMDs strong candidates for a wide range of optoelectronic devices. Here we present a study in which WS2 and the organic J-aggregated dye TDBC are implemented in a microcavity, facilitating hybrid polariton formation at room temperature. TDBC has been shown to enable the strong coupling regime in microcavities before. By embedding the monolayers of WS2 within a grid of silver electrodes we can electrically control the photon mediated hybridisation of Frenkel and Wannier-Mott excitons between maximal mixing coefficients of 17% and 26% in the middle polariton branch [2]. Polariton-polariton interactions give rise to non-linear effects, which make polaritonic systems attractive to observe a multitude of fascinating phenomena such as inversionless lasing, polariton condensation and superfluidity. These interactions are much weaker for localised Frenkel excitons than for Wannier-Mott excitons typical in a crystalline lattice. Our results show how the hybridisation between such distinct excitons could be controlled electrically at room temperature. These findings could open pathways to novel photonic devices with engineered optical properties.


[1] Y. Rong et al. Nanoscale, vol. 6, no. 20, pp. 12096–12103, 2014.
[2] L. C. Flatten et al. arXiv:1608.05274 [cond-mat, physics:physics], 2016. arXiv: 1608.05274.