Host Materials For Semiconductors
OLED has the advantages of active light emission, easy realization of large-screen flexible display, continuous adjustment of light emission color, easy realization of blue light emission, wide viewing angle, simple process, low cost, etc., and has significant applications in many fields. The OLED device is composed of a cathode, an anode, and an organic layer in the middle. The organic layer generally includes an electron transport layer, a light emitting layer, and a hole transport layer. In OLED materials, the host material usually contains a hole and/or electron transport layer, which has suitable carrier transport properties, and its triplet energy level is higher than that of phosphorescent emitters, which can confine the triplet excitons to the light-emitting layer. The host material affects the luminous efficiency of the entire device. In OLED devices, host materials play a vital role. The state of the organic molecules in the OLED device is a thin film state, and the organic material in the thin film state will produce a concentration effect due to the interaction between the molecules, resulting in a sharp drop in the efficiency of the device. Therefore, in general, in an OLED device, doping the guest light-emitting material into the host material can reduce the interaction between the light-emitting molecules, alleviate the concentration quenching effect, and improve the light-emitting efficiency of the OLED device. It can be seen that the host material plays a vital role in OLED devices and affects the application of OLED materials.
Figure 1. The molecular structure of some OLED host materials
Applications:
- Organic Light Emitting Diode (OLED): As an organic light-emitting device, OLED has a wide range of applications in lighting, display, imaging and other fields. In the field of lighting, OLED can be used in interior lighting (LCD office, home, automobile, airplane, etc.), targeted lighting and functional lighting (signage lighting, performance lighting, etc.). And combining OLEDs of different light colors with a flexible substrate can realize integrated lighting without the sense of lighting equipment. OLED lighting has the advantages of energy saving, environmental protection, surface emission, high brightness, and diffuse light source. The application of host materials can significantly improve the luminous efficiency of OLED lighting materials. In the display field, OLED has significant advantages such as low-voltage DC drive, self-luminescence, high brightness, high efficiency, wide viewing angle, low power consumption, ultra-thin, large-area display, and long life. OLED displays can be applied to communication equipment, electronic products, transportation products, commercial products and other equipment, with significant advantages. In the imaging field, the application of host materials enhances the luminous efficiency, which can significantly improve the brightness and contrast in imaging.
Reference
- Xiang-Yang Liu,Yi-Jie Zhang,Xiyu Fei,Quan Ran,Man-Keung Fung,Jian Fan. Diazaspirocycles: novel platforms for efficient phosphorescent organic light-emitting diodes [J]. J. Mater. Chem. C, 2019,7, 1370-1378.
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