Research progress of OLED luminescent materials

Introduction

Chip, display and battery technology are called the three major hardware technologies of the information industry. In the trend of global informationization, countries are vying for the commanding heights of these three technologies, thus gaining the initiative of the entire industry. Here is a brief overview of the key materials for the next generation of display technology. In recent years, with the increasing demand for high quality display devices, (organic light emitting diode) OLED technology has been greatly developed. At present, a variety of OLED products have been put on the market.

 

OLED luminescent materials

Organic electroluminescent materials are the basis of OLED display technology. Organic materials are so important because they have the following characteristics: (1) Organic materials can be formed on any substrates because of their good mechanical processing properties; (2) Many organic illuminants have high Fluorescence quantum efficiency, especially in the blue region and the fluorescence efficiency of some organic matter is almost 100%; (3) The chemical structure of organic matter can be adjusted according to the designer's requirements. According to the molecular size of the OLED optoelectronic materials, they are mainly divided into organic small molecular materials and polymer materials.

 

Organic small molecule materials

In the field of full-color OLED flat panel display, high-efficiency and high-purity red, blue and green primaries have played an extremely important role. Compared with green light materials that have already met commercial requirements, high-efficiency and long-life blue light materials, especially deep blue light materials, are relatively lacking because of the wide energy gap of deep blue light materials. Therefore, the development of new deep blue light materials has become the focus of the current OLED industry. Since its inception as a material for organic electroluminescent devices, anthracene has attracted much attention due to its unique carrier-balancing properties. Most of the blue light luminescent materials currently on the market are anthracene derivatives. 

 

 

Polymer Materials

In 1988, Deng Qingyun reported a layered structure of organic electroluminescent diodes, opening up new areas. In 1990, Burroughes et al. reported an electroluminescent diode using polystyrene (PPV) as luminescent material, which is a brand new LED after transistors and amorphous semiconductors. The organic electroluminescent material is easy to form a thin film, and the required light-emitting driving voltage is low, so it is easier to realize color display than the inorganic material. In 1995, Pei and several other groups independently discovered a light-emitting electrochemical cell with light-emitting diode structure. In 1996, Tessler, Hide, Brouwer discovered optically pumped polymer materials and devices, while the electric pumped polymer laser materials are under study, the latter being more challenging and more promising. In 1998, new progress was made in the field of polymer lasers. It has been observed that the BEH-PPV polymer film can achieve an optical gain of 104 cm-1 at room temperature. They also reported near-diffraction-limited laser emission of polymer BEH-PPV in high-precision planar cavities, which pumped BEH-PPV with ns or fs laser pulses to obtain a whispering gallery pattern in the microring cavity.

 

Conclusion

Organic electroluminescent materials have made breakthroughs in just a few years, and have made remarkable progress, posing a strong challenge to traditional display materials. At present, the research powers is this industry are sparing no great efforts to carry out this work. Although the research on organic electroluminescent materials has achieved great results, there are still some problems to be solved in the process of commercialization of OLEDs, such as basic research on luminescence mechanism; research on materials and devices related to full-color displays; research on three-line luminescent materials and exploration of new organic electroluminescent materials.


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