Impact of triplet absorption and triplet-singlet annihilation on the dynamics of optically pumped organic solid-state lasers

We study the dynamics of a diode pumped organic semiconductor laser based on the polymer-polymer guest-host system F8BT and MEH-PPV. Regardless of the duration of the pump pulse, lasing persists for only a few nanoseconds. In two separate experiments we study in detail the contribution of triplet-singlet annihilation and triplet state absorption. On this basis we were able to model the laser dynamics. As a result, we show that depending on the supplied energy density of the pumping source, triplet-singlet annihilation or triplet state absorption play the prevalent role.