A polythiophene microcavity laser

Abstract

We report photopumped lasing in a microcavity device with a polythiophene layer as the emitter. These microcavity devices are built by joining two polymer coated dielectric mirrors at elevated temperature. When photopumping the film, a lasing threshold is observed at 120 nJ/cm 2. Comparative studies with fast pump–probe spectroscopy of thin polythiophene films and the same polymer in photopumped lasing studies, indicate that the gain coefficient is 80±20 cm −1, and that the exciton concentration is 2×10 17 cm −3 at the lasing transition, well below the exciton–exciton recombination level.