Topologically reconfigurable room-temperature polariton condensates from bound states in the continuum in organic metasurfaces.

An exciton-polariton condensate is a state of matter with collective coherence leading to many fascinating macroscopic quantum effects. Recently, optical bound states in the continuum (BICs) have been demonstrated as peculiar topological states capable of imparting novel characteristics onto the polariton condensates. Organic semiconductors featuring robust Frenkel excitons and high physicochemical tunability potentially offer a promising platform to explore topologically engineering of BIC polariton condensates at room temperature. However, a universal physical mechanism for engineering organic BIC systems has remained elusive, hindering the demonstration of BIC polariton condensates with topologically tunable macroscopic quantum effects. Here we report topologically reconfigurable room-temperature polariton condensates by systematically engineering the BICs in organic semiconductor metasurfaces. Two-dimensional organic metasurfaces are designed to support two polariton BICs with different topological charges. The organic Frenkel excitons with large binding energies allow for non-equilibrium polariton condensation at BICs at room-temperature. By virtue of the excellent physicochemical tunability of organic materials, we further explore the dynamic topological engineering of polariton lasers by manipulating the BICs in situ. Our results fundamentally promote the innovative design and topological engineering of polaritonic materials and devices.