Abstract
An easy-to-access, near-UV-emitting linearly extended B,N-doped heptacene with high thermal stability is designed and synthesized in good yields. This compound exhibits thermally activated delayed fluorescence (TADF) at ambient temperature from a multiresonant (MR) state and represents a rare example of a non-triangulene-based MR-TADF emitter. At lower temperatures triplet-triplet annihilation dominates. The compound simultaneously possesses narrow, deep-blue emission with CIE coordinates of (0.17, 0.01). While delayed fluorescence results mainly from triplet-triplet annihilation at lower temperatures in THF solution, where aggregates form upon cooling, the TADF mechanism takes over around room temperature in solution when the aggregates dissolve or when the compound is well dispersed in a solid matrix. The potential of our molecular design to trigger TADF in larger acenes is demonstrated through the accurate prediction of ΔEST using correlated wave-function-based calculations. On the basis of these calculations, we predicted dramatically different optoelectronic behavior in terms of both ΔEST and the optical energy gap of two constitutional isomers where only the boron and nitrogen positions change. A comprehensive structural, optoelectronic, and theoretical investigation is presented. In addition, the ability of the achiral molecule to assemble on a Au(111) surface to a highly ordered layer composed of enantiomorphic domains of racemic entities is demonstrated by scanning tunneling microscopy.
Original language | English |
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Pages (from-to) | 6588-6599 |
Number of pages | 12 |
Journal | Journal of the American Chemical Society |
Volume | 142 |
Issue number | 14 |
DOIs | |
Publication status | Published - 8 Apr 2020 |
Funding
We thank the Leverhulme Trust (RPG-2016-047). This project has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska Curie grant agreement no. 838885 (NarrowbandSSL) and 812872 (TADFlife). We thank Umicore for their generous supply of catalysts. S.S. acknowledges support from the Marie Skłodowska-Curie Individual Fellowship. S.B. acknowledges support from the Bayrisches Staatsministerium für Wissenschaft und Kunst (Stmwk) in the framework of the initiative “SolTech” as well as from the German Science foundation (DFG) (no. 392306670). Z.Y. acknowledges support from the Chinese Scholarship Council (201606100044) and the University of St. Andrews through a stipend. Computational resources have been provided by the Consortium des Équipements de Calcul Intensif (CÉCI), funded by the Fonds de la Recherche Scientifiques de Belgique (F.R.S.-FNRS) under grant no. 2.5020.11, as well as the Tier-1 supercomputer of the Fédération Wallonie-Bruxelles, infrastructure funded by the Walloon Region under the grant agreement no. 1117545. The authors thank F. Rodella and Prof. P. Strohriegl from Bayreuth University for help with the thermogravimetric analysis.
Funders | Funder number |
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Chinese Scholarship Council | |
Consortium des Equipements de Calcul Intensif | |
Federation Wallonie-Bruxelles | |
Fonds de la Recherche Scientifiques de Belgique | 2.5020.11 |
German Science foundation | |
Marie Sklodowska-Curie | |
Marie Skłodowska-Curie | |
University of St. Andrews | |
Walloon Region | 1117545 |
Horizon 2020 Framework Programme | 838885, 812872 |
Leverhulme Trust | RPG-2016-047 |
University of St Andrews | |
Deutsche Forschungsgemeinschaft | 392306670 |
Fédération Wallonie-Bruxelles | |
China Scholarship Council | 201606100044 |
Bayerisches Staatsministerium für Wissenschaft, Forschung und Kunst | |
Sächsisches Staatsministerium für Wissenschaft und Kunst |
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