Quinacridone dye was firstly synthesized by H. Libermann in 1935, and the molecular structure is shown in Figure 1. However, a mature and practical preparation method was put forward in 1958. Then, quinacridone dyes gradually became an important variety in the coloring industry. Imino group and carbanyl group in quinacridone dye molecular structure can form hydrogen bond. Moreover, the quinacridone dyes molecules have a good planar structure, and the molecules are arranged in layers, which helps to form intermolecular hydrogen bonds. Therefore, quinacridone dyes have the advantages of excellent fastness performance, high light and heat resistance. In addition, the quinacridone dyes can be nano crystallized to further improve transparency and pigmentation.

Figure 1. The molecular structure of quinacridone dye.

Applications:

• Coating field: Quinacridone dyes with excellent fastness performance are high-grade organic dyes mainly including red and purple color. The quinacridone dyes are suitable for advanced industrial finishing coating, including automobile original paint and repair paint. Furthermore, these dyes are also suitable for weather resistant latex paint, which can be used for building coating, textile printing and the others.
• Organic field transistors field: By vapor deposition, quinacridone dyes can be directly used to construct organic field transistors. It has been reported that the migration rate of the organic field transistor prepared by quinacridone dyes can reach to 10-³cm² / Vs. After exposing the device to atmosphere for fifty days, the mobility rate of the device did not change significantly, indicating that it has good stability.

Figure 2. Quinacridone dye applied in organic field transistor.

• Organic solar cell field: Quinacridone dyes can be used to design organic solar cells. For example, when quinacridone derivatives are applied to solar cells, the energy conversion efficiency can be improved. Compared with the quinacridone core, the absorption red shift was observed. Through relevant tests, it is found that the energy conversion efficiency has been promoted.

Figure 3. An example of quinacridone dye applied in organic solar cells.

• Electroluminescent materials field: Quinacridone dye used as the electronic injection layer can improve the life and stability of organic light emitting diode (OLED) devices. For example, quinacridone derivatives are used as the electronic injection layer of OLED. Compared with traditional devices, its stability and efficiency are greatly improved.

Figure 4. The molecular structures of quinacridone derivatives that used in OLED.

Classification:

According to the skeleton structure, quinacridone dyes can be divided into linear and angular types.

• Linear quinacridone dyes: Linear quinacridone dyes can be divided into cis structure and trans structure. The cis quinacridone dyes show yellow color and the trans quinacridone dyes usually show purple or red color. Moreover, the quinacridone dyes have homogeneous polycrystalline phenomenon, which includes eight kinds of crystal structures.
• Angular quinacridone dyes: Angular quinacridone dyes also have cis structure and trans structures and the color are both yellow.

References:

1. Berg D, Nielinger C, Mader W, et al. Quinacridone organic field effect transistors with significant stability by vacuum sublimation[J]. Synthetic Metals, 2009, 159(23-24):2599-2602.
2. Chen J A, Chen T L, Kim B S, et al. Quinacridone-based molecular donors for solution processed bulk-heterojunction organic solar cells[J]. Acs Appl Mater Interfaces, 2010, 2(9):2679-2686.
3. Hai, Bi, et al. Fluorinated quinacridone derivative based organic light-emitting device with high power efficiency[J]. Organic Electronics, 2010, 11, 1180–1184.