OLED【Organic Light Emitting Diode 】
The emission mechanism of an OLED device is when electricity is applied, the light-emitting layer is excited by the recombination energy of holes from the anode and electrons from the cathode. The color of an OLED device is depended on the guest material which is trace doped in the host material in the light-emitting layer. Guest materials exhibited lower energy gap, higher quantum yield, and faster decay lifetime than host materials. Thus, the energy transfer to guest materials from exciton or carrier of host materials via energy transfer and light the OLED device.
The Structure of OLED Device
The basic structure of the OLED Device is formed layer by layer of organic materials between anode and cathode. The structure of the relevant film layer is as follows:
●Substrate: Foundation of the OLED can be plastic, glass, or metal foil
●Anode: A transparent or opaque conductive layer which can generate holes and inject holes into the organic layers.
●Hole Injection Layer (HIL) – HIL is deposited on top of the anode, and this layer receives holes from the anode and injects into next layer.
●Hole Transport Layer (HTL) – HTL is deposited on the HIL, and this layer receives holes from HIL and injects holes into the emissive layer.
●Emissive Layer – Usually composed of a host material and a geust material , accepting holes from the hole transport layer and electrons from the electron transport layer. Electrons and holes recombining in the Emissive layer to form excitons, and excitons generate energy. Finally, the energy is released via emissiving light. The color of the light depends on the energy gap of the guest material.
●Hole blocking layer (HBL): Commonly used to block the holes from the anode, so that the holes are confined within the emissive layer
●Electron Transport Layer (ETL): Transport the electrons from the electron injection layer, and then electrons are transferred into the hole blocking layer.
●Electron Injection Layer (EIL) –This layer receives electron from the canode and injects electron into the ETL.
●Cathode: A transparent or opaque conductive layer generate electrons and inject electron into the organic layers.
- ●High brightness, high contrast
- ●High color saturation
- ●Self-illuminating, no backplane required
- ●Wide operating temperature range
- ●Power saving, low energy consumption
- ●Fast response: By μ second
- ●Light and thin
- ●Super wide angle
OLED terminal application