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Donor–Acceptor Type Pendant Conjugated Molecules Based on a Triazine Center with Depressed Intramolecular Charge Transfer Characteristics as Gain Media for Organic Semiconductor Lasers
Author(s) -
Liu Xu,
Sang Ming,
Lin He,
Liu Chengfang,
Zhang Jialing,
Yi Jianpeng,
Gao Kun,
Lai WenYong,
Huang Wei
Publication year - 2020
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201904548
Subject(s) - intramolecular force , fluorene , amplified spontaneous emission , photochemistry , acceptor , quantum yield , molecule , conjugated system , fluorescence , chemistry , laser , materials science , polymer , stereochemistry , organic chemistry , optics , physics , condensed matter physics
A set of fluorene‐capped pendant conjugated molecules ( T‐m and T‐p ), which consist of a triazine center with three carbazole substituents as the donor–acceptor (D‐A) type pendant structure, were designed, synthesized, and investigated as gain media for organic semiconductor lasers (OSLs). In particular, varying the capping positions of the fluorene units on the pendant core structures results in significantly different intramolecular charge transfer (ICT) properties, where T‐m manifested depressed ICT characteristic and high fluorescence quantum yield. The lowest amplified spontaneous emission (ASE) threshold in neat films was recorded as 1.9 μJ cm −2 for T‐m and 83.8 μJ cm −2 for T‐p , which indicated that the depressed ICT characteristics in the case of T‐m help to enhance the ASE properties. Remarkably, the ASE threshold remained almost unchanged and the ASE spectra showed very small shifts (within 1 nm) for T‐m with film samples annealed up to 180 °C in open air. In contrast, its linear counterpart 2FEtCz‐m showed a clearly increased ASE threshold upon annealing above 100 °C. The results suggest that the selective construction of conjugated pendant molecules with depressed ICT characteristics is beneficial for finely modulating the optical and electrical properties as well as improving the thermostability and photostability, which manifests the great potential as a robust gain media for OSLs.