Designing a stable cathode with multiple layers to improve the operational lifetime of polymer light-emitting diodes

Tae Woo Lee, Mu Gyeom Kim, Sang Hun Park, Sang Yeol Kim, Ohyun Kwon, Taeyong Noh, Jong Jin Park, Tae Lim Choi, Jong Hyeok Park, Byung Doo Chin

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24 Citations (Scopus)

Abstract

The short device lifetime of blue polymer light-emitting diodes (PLEDs) is still a bottleneck for commercialization of self-emissive full-color displays. Since the cathode in the device has a dominant influence on the device lifetime, a systematic design of the cathodestructure isnecessary.Theoperational lifetime of bluePLEDscanbegreatly improved byintroducing a three-layer (BaF 2/Ca/Al) cathode compared with conventional two-layer cathodes (BaF2/Al and Ba/Al). Therefore, the roles of the BaF2 and Ca layers in terms of electron injection, luminous efficiency, and device lifetime are here investigated. For efficient electron injection, the BaF 2 layer should be deposited to the thickness of at least one monolayer (̃3 nm). However, it is found that the device lifetime does not showastrong relation withtheelectroninjection orluminousefficiency. Inorder to prolong the device lifetime, sufficient reaction between BaF2 and the overlying Ca layer should take place during the deposition where the thickness of each layer is around that of a monolayer.

Original languageEnglish
Pages (from-to)1863-1868
Number of pages6
JournalAdvanced Functional Materials
Volume19
Issue number12
DOIs
Publication statusPublished - 2009 Jun 23

All Science Journal Classification (ASJC) codes

  • Chemistry(all)
  • Materials Science(all)
  • Condensed Matter Physics

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    Lee, T. W., Kim, M. G., Park, S. H., Kim, S. Y., Kwon, O., Noh, T., Park, J. J., Choi, T. L., Park, J. H., & Chin, B. D. (2009). Designing a stable cathode with multiple layers to improve the operational lifetime of polymer light-emitting diodes. Advanced Functional Materials, 19(12), 1863-1868. https://doi.org/10.1002/adfm.200801620