Suppressing Photobleaching of J-Aggregates via Strong Light-Matter Coupling

Surface plasmon polaritons (SPPs) are confined electromagnetic modes at a metal-dielectric interface, generating intense near-field forces on ultrafast timescales. When an organic emitter interacts with these SPP fields, they can form hybrid polaritonic states with distinct energy levels, evidenced by anti-crossing in the dispersion relation, known as Rabi splitting [1]. It has been shown that chemical reactivity, charge, and exciton transport [2], can be modified under strong coupling conditions. The photobleaching effect is one such fundamental chemical property appearing in many organic molecules, suppressing the fluorescence of dye molecules and leading to irreversible photodamage. Photobleaching occurs through photodynamic interactions, where dye molecules in an excited triplet state interact with atmospheric oxygen, which is also in its triplet state, via a charge transfer mechanism generating reactive oxygen species, which in turn chemically degrade the fluorophores [3]. Since polaritonic states are coherent hybrids of plasmons and excitons they have extremely short lifetimes (~ 10fs) far faster than typical intersystem crossing rates (10–<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">8</sup> to 10–<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> seconds). This prevents efficient triplet state population, making polaritonic states highly effective in suppressing photobleaching reactions [4].