Electroluminescence of tetradentate Pt(II) complexes: O^N^N^O versus C^N^N^O coordination


  • Piotr Pander Faculty of Chemistry, Silesian University of Technology, Strzody 9, 44-100 Gliwice, Poland & Centre for Organic and Nanohybrid Electronics, Silesian University of Technology, Konarskiego 22B, 44-100 Gliwice, Poland ,
  • Larissa Gomes Franca Department of Physics, Durham University, Durham, South Road, DH1 3LE, UK ,
  • Fernando Dias Department of Physics, Durham University, Durham, South Road, DH1 3LE, UK ,
  • Valery Kozhevnikov Department of Applied Sciences, Faculty of Health and Life Sciences, Northumbria University, Newcastle Upon Tyne, Tyne and Wear NE1 8ST, UK


Alkylation of one of the phenolic hydroxyl groups in a silene-type tetradentate ligand changes the coordination mode from O^N^N^O to cyclometallating C^N^N^O type. The ligand was used to synthesise a new cyclometallated luminescent Pt(II) complex 2. While in solution the complex is poorly luminescent, in the solid state the emission is reinstated which allowed to evaluate the complex 2 as phosphorescent emitter in organic light emitting devices (OLEDs). 2 displays EQE = 9.1 % and maximum luminance of 9000 cd m-2 in a vacuum deposited device. We carried out comparative analysis of photo- and electroluminescence of complex 2 with O^N^N^O complex 1 and demonstrated that the similar luminescent properties of O^N^N^O and C^N^N^O complexes are rather coincidental as they display different excited state landscapes. Surprisingly, the two complexes display a dramatically different electrochemical behaviour with the O^N^N^O coordination leading to formation of a stable electropolymer, but C^N^N^O coordination fully preventing electropolymerisation.


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