Determination of Oscillator Strength of CdSe Nanoplatelets from Strong Light-Matter Coupling

Strong light-matter coupling exists as a tool to alter the nature of both hybridized matter and photon states, with interaction dependent upon the oscillator strength of the matter, and mode volume of the photon. CdSe nanoplatelets (NPLs) are a unique system to probe the effects of varying oscillator strength on polariton photophysics due to their ability to form heterostructures with CdS, however, the oscillator strength of such heterostructures is unknown – even the oscillator strength of core-only NPLs has been under recent question. We report exciton-polaritons formed from core-only, core-crown, and core-shell NPLs, which, alongside finite-difference time-domain (FDTD) simulations of Fabry-Pérot cavity mode volume, allow for the verification of core-only and determination of core-crown and core-shell oscillator strengths. Additionally, we show that polaritons can be used not only as a means of altering the properties of coupled emitters, but as an analytical tool to better understand the properties of coupled emitters.