Controlling singlet–triplet splitting in carbazole–oxadiazole based bipolar phosphorescent host materials

Kautny, Paul; Wu, Zhongbin; Stöger, Berthold; Tissot, Antoine Michel; Horkel, Ernst; Chen, Jiangshan; Ma, Dongge; Hagemann, Hans-Rudolf; Fröhlich, Johannes; Lumpi, Daniel

doi:10.1016/j.orgel.2014.11.027

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Title		Controlling singlet–triplet splitting in carbazole–oxadiazole based bipolar phosphorescent host materials
Authors		Kautny, Paul Wu, Zhongbin Stöger, Berthold Tissot, Antoine Michel Horkel, Ernst Chen, Jiangshan Ma, Dongge Hagemann, Hans-Rudolf Fröhlich, Johannes Lumpi, Daniel show all authors [1 - 10]
Published in		Organic Electronics. 2015, vol. 17, p. 216-228
Abstract		A rational molecular design strategy for carbazole–oxadiazole based bipolar host materials was developed to improve the device efficiency of blue phosphorescent organic light-emitting diodes (PHOLED). Steric effects of strategically placed methyl groups led to an increase of triplet energies (o-2MPCzPOXD: 2.66 eV and o-3MPCzPOXD: 2.73 eV versus the initial host material o-PczPOXD: 2.62 eV) while less pronouncedly affecting singlet energies and, therefore, retaining low driving voltages, high power efficiencies and remarkably low efficiency roll-offs in PHOLEDs. The maximum quantum efficiencies (EQE) for blue devices (FIrpic) were significantly raised for o-2MPCzPOXD (13.6%) and o-3MPCzPOXD (11.5%) versus o-PCzPOXD (9.0%) although yielding comparable values for green devices (Ir(ppy)3; 12.9% and 15.4% versus 13.2%). Supported by theoretical calculations a structure–property relationship was established from photo-physical properties, PHOLED performance measurements and structural characterization from single crystal data.
Identifiers		DOI: 10.1016/j.orgel.2014.11.027
Full text		Article (Published version) (1.9 MB) - Limited access to UNIGE Other version: http://linkinghub.elsevier.com/retrieve/pii/S1566119914005497
Structures		Faculté des sciences / Section de chimie et biochimie / Département de chimie physique
Research group		Groupe Hagemann
Citation (ISO format)		KAUTNY, Paul et al. Controlling singlet–triplet splitting in carbazole–oxadiazole based bipolar phosphorescent host materials. In: Organic Electronics, 2015, vol. 17, p. 216-228. doi: 10.1016/j.orgel.2014.11.027 https://archive-ouverte.unige.ch/unige:44949