Enhanced Optical Gain Through Efficient Polaron Pairs Recombination in F8xBTy

Yongjie Huang, Qi Wei, Yi Jiang*, Hoi Lam Tam, King Fai Li, Zhan-Bo Jia, Yu Yan, Chen Sun, Mingjie Li*, Man Shing Wong, Kok Wai Cheah*

*Corresponding author for this work

Research output: Contribution to journalJournal articlepeer-review

Abstract

Organic semiconductors combine excellent optoelectronic properties with simple fabrication to obtain the desired features by tuning their chemical structures. Förster resonant energy transfer (FRET) is in designing blended gain media, but it does not enhance efficient optical gain in most cases. This is due to the competition between polaron pairs and stimulated emission (SE), leading to quenching of SE. Thus a challenge to design efficient optical gain systems via FRET. Here, a series of copolymers, F8xBTy, through uniformly inserting benzothiadiazole (BT) units into the 9,9-dioctylfluorene (F8) chain, were synthesized. They consist of both charge transfer (CT) and FRET is synthesized. These copolymers can prevent the local F8 aggregation and lead to efficient polaron pair recombination into singlet excitons. The F8 excitons are thus spatially confined, increasing efficient SE. Efficient light amplification has low amplified spontaneous emission (ASE) thresholds (as low as 5.3 µJ cm−2) and significantly enhanced optical gain with gain coefficients up to 37 cm−1. The distributed feedback (DFB) lasers has low lasing thresholds down to 5.4 nJ per pulse. The results suggest that these copolymers provide a organic gain media design strategy with efficient optical gain, introducing a new approach to developing laser materials for electrically pumped lasers.
Original languageEnglish
Article number2402455
Number of pages10
JournalAdvanced Optical Materials
DOIs
Publication statusE-pub ahead of print - 30 Dec 2024

Scopus Subject Areas

  • Electronic, Optical and Magnetic Materials
  • Atomic and Molecular Physics, and Optics

User-Defined Keywords

  • organic semiconductor lasers
  • polaron pairs
  • semiconducting copolymers
  • stimulated emission

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