An inconvenient influence of iridium(III) isomer on OLED efficiency

Research output: Contribution to journalArticlepeer-review


  • Etienne Baranoff
  • Henk J. Bolink
  • Filippo De Angelis
  • Simona Fantacci
  • Davide Di Censo
  • Karim Djellab
  • Michael Grätzel
  • Md Khaja Nazeeruddin

Colleges, School and Institutes

External organisations

  • Istituto Italiano di Tecnologia
  • Fundació General de la Universitat de Valencia (FGUV)
  • Laboratory for Photonics and Interfaces
  • Laboratory of Photonics and Interfaces, Institute of Chemical Sciences and Engineering, École Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland.
  • Instituto de Ciencia Molecular, Universidad de Valencia
  • Universidad de Valencia
  • C/o Dipartimento di Chimica
  • Università di Perugia
  • Italian Institute of Technology (IIT)
  • Center for Biomolecular Nanotechnologies
  • Université de Picardie Jules Verne
  • School of Basic Sciences
  • Istituto CNR di Scienze e Tecnologie Molecolari (ISTM-CNR)
  • Plate-forme de Microscopie


The recently reported heteroleptic cyclometallated iridium(III) complex [Ir(2-phenylpyridine)2(2-carboxy-4-dimethylaminopyridine)] N984 and its isomer N984b have been studied more in detail. While photo- and electrochemical properties are very similar, DFT/TDDFT calculations show that the two isomers have different HOMO orbital characteristics. As a consequence, solution processed OLEDs made using a mixture of N984 and isomer N984b similar to vacuum processed devices show that the isomer has a dramatic detrimental effect on the performances of the device. In addition, commonly used thermogravimetric analysis is not suitable for showing the isomerization process. The isomer could impact performances of vacuum processed OLEDs using heteroleptic cyclometallated iridium(III) complexes as dopant.


Original languageEnglish
Pages (from-to)8914-8918
Number of pages5
JournalDalton Transactions
Issue number38
Publication statusPublished - 14 Oct 2010

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