Pyrene-capped starburst emitters as gain media for organic lasers: design, synthesis, and stabilized lasing properties

A set of pyrene-capped starburst organic emitters composed of a non-planar cross-shaped spirofluorene core (SF-PyF) and a large rigid planar pyrene core (Py-PyF) have been designed, synthesized and explored as efficient emitters for organic lasers. High photoluminescence yields and excellent thermal stability of SF-PyF and Py-PyF in neat films make them promising optical gain media. Low amplified spontaneous emission (ASE) thresholds of 6.6 mu J cm(-2) (1.3 kW cm(-2)) at 451 nm for SF-PyF and 5.4 mu J cm(-2) (1.1 kW cm(-2)) at 490 nm for Py-PyF were obtained (pump pulse: lambda(p) = 355 nm, 10 Hz, 5 ns). Distributed feedback (DFB) lasers based on SF-PyF and Py-PyF exhibited good performance with low thresholds (16 nJ per pulse for SF-PyF and 24 nJ per pulse for Py-PyF, respectively) and the full width at half maximum of about 0.2 nm. Surprisingly, DFB lasers integrated with SF-PyF and Py-PyF as gain media exhibited excellent ambient photostability and superior reliability even in hot water (80 degrees C). The excellent stability of ASE spectra, electroluminescence spectra and lasing spectra under harsh conditions manifests that the resulting pyrene-capped starburst emitters are beneficial for improving the lasing stability issues. The study sheds light on exploring robust organic gain media toward electrically pumped OSLs.