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Title: Fluorene- and benzofluorene-cored oligomers as low threshold and high gain amplifying media

Deliberate control of intermolecular interactions in fluorene- and benzofluorene-cored oligomers was attempted via introduction of different-length alkyl moieties to attain high emission amplification and low amplified spontaneous emission (ASE) threshold at high oligomer concentrations. Containing fluorenyl peripheral groups decorated with different-length alkyl moieties, the oligomers were found to express weak concentration quenching of emission, yet excellent carrier drift mobilities (close to 10{sup −2} cm{sup 2}/V/s) in the amorphous films. Owing to the larger radiative decay rates (>1.0 × 10{sup 9 }s{sup −1}) and smaller concentration quenching, fluorene-cored oligomers exhibited down to one order of magnitude lower ASE thresholds at higher concentrations as compared to those of benzofluorene counterparts. The lowest threshold (300 W/cm{sup 2}) obtained for the fluorene-cored oligomers at the concentration of 50 wt % in polymer matrix is among the lowest reported for solution-processed amorphous films in ambient conditions, what makes the oligomers promising for lasing application. Great potential in emission amplification was confirmed by high maximum net gain (77 cm{sup −1}) revealed for these compounds. Although the photostability of the oligomers was affected by photo-oxidation, it was found to be comparable to that of various organic lasing materials including some commercial laser dyes evaluated under similar excitation conditions.
Authors:
; ; ; ; ;  [1] ;  [2]
  1. Institute of Applied Research, Vilnius University, Saulėtekio 9-III, LT-10222 Vilnius (Lithuania)
  2. Department of Solid State Electronics, Vilnius University, Saulėtekio 9-III, LT-10222 Vilnius (Lithuania)
Publication Date:
OSTI Identifier:
22486390
Resource Type:
Journal Article
Resource Relation:
Journal Name: Applied Physics Letters; Journal Volume: 107; Journal Issue: 4; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; ABUNDANCE; CARRIERS; CONTROL; DYES; EMISSION; EXCITATION; FILMS; FLUORENE; GAIN; LASERS; MATERIALS; MATHEMATICAL SOLUTIONS; MATRICES; MOBILITY; OXIDATION; QUENCHING; RADIATIVE DECAY