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Scrutinizing Design Principles toward Efficient, Long-Term Stable Green Light-Emitting Electrochemical Cells

TitleScrutinizing Design Principles toward Efficient, Long-Term Stable Green Light-Emitting Electrochemical Cells
Publication TypeJournal Article
Year of Publication2017
AuthorsNamanga, JE, Gerlitzki, N, Mudring, AV
JournalAdvanced Functional Materials
Volume27
Pagination1605588
Date Published05
Type of ArticleArticle
ISBN Number1616-301X
Accession NumberWOS:000400449200003
Keywordsancillary ligand, blue, chemistry, cyclometalated iridium(iii) complexes, devices, electroluminescence, emitters, Materials Science, phosphorescent, physics, Technology - Other Topics
Abstract

-bipyridine (4) are synthesized and characterized. All complexes emit in the green region of light with emission maxima of 529-547 nm and photoluminescence quantum yields in the range of 50.6%-59.9%. LECs for electroluminescence studies are fabricated based on these complexes. The LEC based on (1) driven under pulsed current mode demonstrated the best performance, reaching a maximum luminance of 1605 cd m(-2) resulting in 16 cd A(-1) and 8.6 lm W-1 for current and power efficiency, respectively, and device lifetime of 668 h. Compared to this, LECs based on (3) and (4) perform lower, with luminance and lifetime of 1314 cd m(-2), 45.7 h and 1193 cd m(-2), 54.9 h, respectively. Interestingly, in contrast to common belief, the fluorine content of the Ir-iTMCs does not adversely affect the LEC performance, but rather electron donating substituents on the (NN)-N-boolean AND ligands are found to dramatically reduce both performance and stability of the green LECs. In light of this, design concepts for green light emitting electrochemical devices have to be reconsidered.

DOI10.1002/adfm.201605588
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CMI

Alternate JournalAdv. Funct. Mater.