Optically pumped lasing in a single crystal cavity of thiophene/phenylene co-oligomers grown via improved crystal growth methods in solution

Abstract

Single crystals of thiophene/phenylene co-oligomers (TPCOs) are promising organic laser media. Owing to their poor solubility in solvents, single crystals of TPCOs have conventionally been grown using sublimation processes. However, the morphology of the grown crystals is not ideal for lasing by the self-cavity effect. In this report, single crystals of 5,5‴-bis(4-biphenylyl)-2,2′:5′,2″:5″,2‴-quaterthiophene (BP4T), which is one of the longest TPCOs, are grown through improved methods in solution to achieve lasing with a well-shaped single crystal cavity. The high quality factors (5.9 × 103) and group refractive indexes (>3.5) suggest that the obtained crystals are superior organic laser media.