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High-Efficiency Saturated Red Bilayer Light-Emitting Diodes: Comparative Studies with Devices from Blend of the Same Light-Emitting Polymers |
| ZHANG Yong1,2;HOU Qiong3;MO Yue-Qi1;PENG Jun-Biaov;CAO Yong1 |
| 1Institute of Polymer Optoelectronic Material and Devices, Key Laboratory of Specially Functional Materials and Advanced Manufacturing Technology, South China University of Technology, Guangzhou 510640
2Institute of Optoelectronic Material and Technology, South China Normal University, Guangzhou 510631
3Department of Chemistry, South China Normal University, Guangzhou 510631 |
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| Cite this article: |
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ZHANG Yong, HOU Qiong, MO Yue-Qi et al 2006 Chin. Phys. Lett. 23 1015-1018 |
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Abstract High-efficient saturated red light-emitting diodes are realized based on a bilayer of phenyl-substituted poly [p-phenylene vinylene] derivative (P-PPV) and {copolymer (PFO-DBT15) of 9,9-dioctylfluorene (DOF) and 4,7-di-2-thienyl-2,1,3-benzothiadiazole (DBT)}. External electroluminescent (EL) quantum efficiency of PFO-DBT15 is increased from 1.6% for a single-layer device to 4.7% for the bilayer device by insertion of a P-PPV layer between PEDOT (polyethylene dioxythiophene-polystyrene sulfonic acid) and PFO-DBT15 at the current density of 35mA/cm2. The luminescence efficiency reaches 0.83cd/A, and the Commission Internationale de I'Eclairage coordinates (CIE) become nearly x=0.700 and y=0.300. In comparison with the devices from PFO-DBT15 and P-PPV blend films, the P-PPV/PFO-DBT15 bilayer device shows higher EL quantum efficiency and better stability under high current density. The improved device performance can be attributed to the charge-confinement effect at the interface of the P-PPV/PFO-DBT15 bilayer structure.
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| Keywords:
78.60.Fi
78.66.Qn
85.60.Jb
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Published: 01 April 2006
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