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An Improved Blue Polymer Light-Emitting Diode by Using Sodium Hydroxide/Ca/Al Cathode |
| MA Liang1,2;XIE Zhi-Yuan1;LIU Jun1;YANG Jun-Wei1;CHENG Yan-Xiang1;WANG Li-Xiang1;WANG Fo-Song1 |
| 1State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry,
Changchun 130022
2Graduate School of the Chinese Academy of Sciences, Chinese Academy of Sciences, Changchun 130022 |
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| Cite this article: |
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MA Liang, XIE Zhi-Yuan, LIU Jun et al 2005 Chin. Phys. Lett. 22 3196-3188 |
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Abstract The performance of blue polymer light-emitting diodes (PLEDs) based on poly(9,9-dioctylfluorene) (PFO) is improved by introducing a thin layer of sodium hydroxide (NaOH) between the calcium cathode and the PFO emissive layer. By replacing the commonly used Ca/Al cathode by a NaOH (2.5nm)/Ca (10nm)/Al cathode, the driving voltage is reduced from 8.3V to 5.4V and the light-emitting efficiency is enhanced from 0.46cd/A to 0.72cd/A for achieving a luminance of 500cdm2, respectively. Moreover, the device with NaOH/Ca/Al cathode shows a pure blue emission of (0.17, 0.12) at high brightnesses. These improvements are attributed to introduction of a thin layer of NaOH that can lower the interfacial barrier and facilitate electron injection.
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| Keywords:
78.60.Fi
85.60.Jb
78.66.Qn
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Published: 01 December 2005
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