Bis(Triphenylamine)Benzodifuran Chromophores: Synthesis, Electronic Properties and Application in Organic Light-Emitting Diodes

Hui Li; Ryutaro Komatsu; Jihane Hankache; Hisahiro Sasabe; Latevi Max Lawson Daku; Bilal Özen; Songjie Chen; Jürg Hauser; Andreas Hauser; Silvio Decurtins; Junji Kido; Shi-Xia Liu

doi:10.3389/fchem.2021.721272

Bis(Triphenylamine)Benzodifuran Chromophores: Synthesis, Electronic Properties and Application in Organic Light-Emitting Diodes

Front Chem. 2021 Jul 21:9:721272. doi: 10.3389/fchem.2021.721272. eCollection 2021.

Authors

Affiliations

¹ Department of Chemistry, Biochemistry and Pharmaceutical Sciences, University of Bern, Bern, Switzerland.
² Department of Organic Device Engineering Research Center for Organic Electronics, Yamagata University, Yamagata, Japan.
³ Department of Physical Chemistry, University of Geneva, Geneva, Switzerland.

Abstract

A series of bis(triphenylamine)benzodifuran chromophores have been synthesized and fully characterised. Starting from suitably functionalized benzodifuran (BDF) precursors, two triphenylamine (TPA) moieties are symmetrically coupled to a central BDF unit either at 4,8-positions through double bonds (1) and single bonds (2) respectively, or at 2,6-positions through double bonds (3). Their electronic absorption and photoluminescence properties as well as redox behaviour have been investigated in detail, indicating that the π-extended conjugation via vinyl linkers in 1 and 3 leads to comparatively strong electronic interactions between the relevant redox moieties TPA and BDF. Due to intriguing electronic properties and structural planarity, 3a has been applied as a dopant emitter in organic light-emitting diodes. A yellowish-green OLED exhibits a high external quantum efficiency (EQE) of 6.2%, thus exceeding the theoretical upper limit most likely due to energy transfer from an interface exciplex to an emissive layer and/or favorable horizontal orientation.

Keywords: benzodifuran; optical spectroscopy; organic light-emitting diode; spectroelectrochemistry; triphenylamine.