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Keywords:

  • blue light emission;
  • optical gain properties;
  • organic semiconductor lasers;
  • pyrene-cored dendrimers;
  • thermal stability

Abstract

Here, a detailed characterization of the optical gain properties of sky-blue-light-emitting pyrene-cored 9,9-dialkylfluorene starbursts is reported; it is shown that these materials possess encouragingly low laser thresholds and relatively high thermal and environmental stability. The materials exhibit high solid-state photoluminescence (PL) quantum efficiencies (>90%) and near-single-exponential PL decay transients with excited state lifetimes of ∼1.4 ns. The thin-film slab waveguide amplified spontaneous emission (ASE)-measured net gain reaches 75–78 cm−1. The ASE threshold energy is found to remain unaffected by heating at temperatures up to 130 °C, 40 to 50 °C above Tg. The ASE remained observable for annealing temperatures up to 170 or 200 °C. 1D distributed feedback lasers with 75% fill factor and 320 nm period show optical pumping thresholds down to 38–65 Wcm−2, laser slope efficiencies up to 3.9%, and wavelength tuning ranges of ∼40 nm around 471–512 nm. In addition, these lasers have relatively long operational lifetimes, with N1/2 ≥ 1.1 × 105 pulses for unencapsulated devices operated at ten times threshold in air.