Dynamics of Spin‐Dependent Polariton–Polariton Interactions in Two‐Dimensional Layered Halide Organic Perovskite Microcavities

Abstract

Half-light and half-matter exciton polaritons have demonstrated profound impacts on coherent quantum phenomena. Two-dimensional (2D) organic−inorganic perovskite semiconductors, exhibiting large exciton binding energy and spin-based behavior, are an excellent platform for the study of exciton polaritons at room temperature. However, the implementation of these fascinating coherent phenomena is still constrained by the lack of an understanding of the crucial polariton-polariton interaction effects. Here, an experimental observation of spin-dependent polariton-polariton interactions in a prototype 2D organic−inorganic perovskite microcavity by circularly polarization-resolved transient absorption (TA) measurements is reported. A power-dependent blue shift of the lower polariton bands with the same spin is clearly revealed, whereas the energy band of the polariton bands with the opposite spin is almost not changed. Spectacularly, it is found that the energy band blue shift mainly takes place before the spin depolarization, which provides accurate evidence for the spin-dependent polariton-polariton interactions. Furthermore, the strong coherent polariton-phonon coupling of perovskite microcavity has also been detected firstly in ultrafast TA dynamics. These results demonstrate that microcavity polaritons inheriting the matter properties from their excitonic constituents exhibit strong nonlinear interactions and pave the way for realizing coherent quantum phenomena at room temperature.

Controlling Exciton/Exciton Recombination in 2-D Perovskite Using Exciton–Polariton Coupling

“…A Fabry–Pérot microcavity consists of two partially reflective mirrors and has been demonstrated for room-temperature polariton formation, manipulation, lasing, and condensation . The strength of the exciton/polariton coupling in such cavities can be controlled by controlling the quality factor, the relative layer thicknesses inside the cavity, and other aspects such as temperature and polarization. , …”

“…7 The strength of the exciton/polariton coupling in such cavities can be controlled by controlling the quality factor, the relative layer thicknesses inside the cavity, and other aspects such as temperature and polarization. 8,9 2D transition metal dichalcogenides (2D-TMDCs) with strong light absorption and large exciton binding energies have been proposed and some have been demonstrated to offer a distinctive platform to achieve room temperature strong coupling. 10 Similarly, 2D metal-halide perovskites as another class of 2D semiconductors exhibit intriguing optoelectronic properties, including high optical absorption, large and tunable exciton binding energies, 11 and high carrier mobilities, while showcasing a unique set of excitonic effects that becomes more pronounced as they transition from the bulk to the confined multiple quantum wells structure of the 2D configuration (e.g., metal-halide layer thickness).…”

“… 7 The strength of the exciton/polariton coupling in such cavities can be controlled by controlling the quality factor, the relative layer thicknesses inside the cavity, and other aspects such as temperature and polarization. 8 , 9 …”

Quasi-two dimensional Ruddlesden-Popper halide perovskites for laser applications

“…The lasing modes are extended states caused by random grain structures in the solution processing that can span the entire pump volume. Also, Roy et al [94] produced a FA-(N-MPDA) PbBr 4 hybrid perovskite with high quality by employing a constant temperature slow evaporation approach with the aid of a long-chain organic diamine spacer. By utilizing the defects and dislocations as well as grain boundaries as scattering centers, they achieved a low-threshold random laser in the well-shaped high-crystallinity nanorods, with extremely small spectral width (~0.1 nm) and high Q-factor (~5350).…”

Origin of Exciton–Polariton Interactions and Decoupled Dark States Dynamics in 2D Hybrid Perovskite Quantum Wells

“…Among high binding energy materials suitable for RT operation, lead-halide perovskites hold a central role. Recent results have shown polariton condensation, parametric scattering, and superfluidity up to RT, with an interaction strength comparable to that of GaAs-based microcavities, that makes perovskites highly attractive. − In this respect, although many studies have been focused on hybrid organic–inorganic 3D perovskites, 2D perovskites, consisting of inorganic layers of [PbX 6 ] 4– octahedra (with the halogen X = Cl, Br, or I) sandwiched between two layers of organic cations, offer enhanced environmental stability and higher tunability if compared to the 3D counterpart. − The pronounced quantum confinement experienced by excitons in the natural multiple quantum-well (QW) structure leads to narrow and robust Wannier-Mott-type excitonic transitions. However, such a high binding energy, in general obtained for a single inorganic layer of [PbX 6 ] 4– (n1) surrounded by two organic ones, inevitably leads to a rather small exciton Bohr radius.…”