Maksim Lednev

Strong interactions between excitons and photons lead to the formation of exciton‐polaritons, which possess different properties compared to their constituents. Polaritons are created by incorporating a dye in an optical cavity where the electromagnetic field is tightly confined. The interest in the subject has exploded in recent years due to the ability to change (photo)chemistry, but still as simple a variable as the yield of emission varies between studies. For the field to progress, linking observables to system parameters is a dire need. Here, the study pairs emission yield to the size of the so‐called exciton reservoir, which dictates polariton relaxation dynamics. To do this, a method is devised to experimentally control the relative size of the exciton reservoir and link it to the yield of emission. Thus, the results enable comparison of the photophysics of previous studies within the field and provide the tools to study the effect of the exciton reservoir on polariton photochemistry.