Spectroscopy of strongly-coupled organic-semiconductor microcavities

By placing a J-aggregated organic semiconductor dye in a microcavity, strong-coupling can be evidenced at room temperature, making such systems ideal for exploration of polariton physics. Using CW photoluminescence (PL) spectroscopy, the different mechanisms by which excitons are able to populate polariton states along the upper and lower polariton branches are revealed. Such strong-coupled microcavities can be adapted to emit polariton electroluminescence. The emission efficiency of polariton OLEDs is characterized and compared with regular weak coupled structures. It is concluded the reduced efficiency of the strong-coupled device is limited by the slow-rate at which exctions scatter into polariton states along the upper and lower polariton branches.