Improvement of the quasi-continuous-wave lasing properties in organic semiconductor lasers using oxygen as triplet quencher

Abstract

We demonstrate quasi-continuous-wave lasing in solvent-free liquid organic semiconductor distributed feedback lasers based on a blend containing a liquid 9-(2-ethylhexyl)carbazole host doped with a blue-emitting heptafluorene derivative. The liquid gain medium is bubbled with either oxygen or nitrogen in order to investigate the role of a triplet quencher such as molecular oxygen on the quasi-continuous-wave lasing properties of organic semiconductor lasers. The oxygenated laser device exhibits a low threshold of 2 μJ cm−2, which is lower than that measured in the nitrogenated device and is independent of the repetition rate in a range between 0.01 and 4 MHz.