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Chemphyschem. 2018 Jul 17;19(14):1711-1715. doi: 10.1002/cphc.201800025. Epub 2018 May 29.

Enhancing the Kinetic Stability and Lifetime of Organic Light-Emitting Diodes based on Bipolar Hosts by using Spiroconjugation.

Author information

1
Samsung Advanced Institute of Technology, Suwon, Gyeonggi-do, 16678, South Korea.
2
Department of Chemistry, North Carolina State University, Raleigh, NC 27695-8204, USA.
3
State Key Laboratory of Crystal Materials Shandong University, Jinan, China, 250100.
4
State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter (FJIRSM), Chinese Academy of Sciences (CAS), Fuzhou, China, 350002.

Abstract

We examined how to enhance the lifetime of organic light-emitting diodes (OLEDs) based on bipolar host molecules ET-HT, where ET and HT refer to electron- and hole-transporting units, respectively, by analyzing their thermodynamic and kinetic stabilities. Our DFT calculations reveal that the thermodynamic stability of ET-HT is determined by that of its anion, which is difficult to improve by chemical modifications of ET and HT. The kinetic stability of ET-HT can be enhanced by the spiroconjugation between ET and HT, which occurs when their π-frameworks are extended and have an orthogonal arrangement. Green OLED devices were fabricated by using ET-HTs with and without spiroconjugation, to find that the device with spiroconjugation has a lifetime that is approximately 6 times longer than the one without spiroconjugation.

KEYWORDS:

OLED; bipolar host; kinetic stability; lifetime; spiroconjugation

PMID:
29719110
DOI:
10.1002/cphc.201800025

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