What is LED?
Light Emission Diode
Using P-N Junction
Wave length is defined
by Element’s Band Gap
Compound Red, Green, Blue
↓
Express Color!(white…)
Core : 2~10 nm
- Ⅱ-Ⅳ element (CdSe, CdTe, Cds)
Shell
- metallic molecular plating(ZnS, ZnSe)
Polymer Coating
- To disperse in the aqueous solution
Absorption: 외부에서 photon이 흡수되는 과정으로, semiconductor의 bandgap보다 큰 에너지를 가지는 경우에만 흡수 된다. 단 bandgap보다 너무 큰 경우는 auger electron을 생성하므로 실질적인 absorption을 일으키지 못한다.
Generation: absorption으로 electron이 excite 되면서 electron-hole pair가 생성된다
Separation: 이 두 carrier들
Property of LED
High efficiency for converting electron to photon (Low power consumption, 1/8 of light bulb, ½ of Fluorescent lamp)
Tiny light sources→Miniaturization, Weight lightening
Semipermanent life span
Fast reaction rate for change
Excellent durability and Eco-friendly
Produce RGB full color as blue LED commercialized
Various application
Although focus on specific band, gen
An organic light emitting diode (OLED) is a solid state device like the LED but composed of several layers in which the emissive electroluminescent layer is a film of organic compounds which emit light in response to an electric current.
Function of each part
Cathode : injecting electron composed of metal
Anode : injecting hole composed of transparent ITO
Emissive polymer : reco