Browsing by Author "Ho, GK"

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Color-tunable multilayer light-emitting diodes based on conjugated polymers
(2004-02-16)
Huang, CC
;
Meng, HF
;
Ho, GK
;
Chen, CH
;
Hsu, CS
Wide-range low-voltage continuous color tuning is achieved in multilayer light-emitting diodes based exclusively on the commonly used high-efficiency electroluminescent conjugated polymers. There are three layers for red, green, and blue emission, and one extra layer for electron blocking. The color of the emitted photon depends on the position of the electron-hole recombination. Due to the stronger field dependence of the electron mobility relative to the hole mobility, the recombination zone is pushed away from the cathode and concentrated in different emissive layers as the voltage increases. (C) 2004 American Institute of Physics.
Efficient white light emission in conjugated polymer homojunctions
(2004-11-15)
Ho, GK
;
Meng, HF
;
Lin, SC
;
Horng, SF
;
Hsu, CS
We study polymer light-emitting diodes with a homojunction, i.e., junction between two layers with the same host material. One layer is poly (9,9-dioctylfluorene-2,7-diyl) (PFO) host blended with a small amount of poly (2-methoxy-5 (2'-ethyl-hexyloxy)-1,4-phenylene vinylene), another layer is either pure PFO or PFO host blended with green-emitting polyfluorene copolymers. Such homojunction devices are solution processed and show efficient white light emission. The peak luminance 3000 cd/m(2) is reached at 10 V with Internationale de L'Eclairage (CIE) coordinate (0.34, 0.34). (C) 2004 American Institute of Physics.