Why are persistence luminescence materials mostly green?

Safe passage signs are common in our daily life. Interestingly, they can even emit green light without power supply. This phenomenon is mainly due to self-luminous materials, which are very safe and healthy. However, most of us have questions about the color of the inorganic self-luminous material. Today, we are going to introduce the reason why the self-luminous material is green.

 

Generally speaking, the luminous intensity of the self-luminous materials is much weaker than the normal luminescence. It is almost invisible in daylight or light, and blue or green light are more easily observed in dark environments. In addition, self-luminous materials have unique advantages in the conversion and utilization of the solar energy . They can store solar energy during the day and slowly release it at night. Therefore, it is an important class of light conversion materials and energy-saving materials.

 

Self-luminous materials also have historical reasons for their green appearance. From the night pearls recorded in ancient writings to the first generation of inorganic light storage materials that appeared in 1866, they are all green self-luminous materials. The luminescent mechanism of nocturnal pearl is the same as that of general persistence luminescent materials, which is caused by some heavy metal impurities in the matrix. It often has yellow green, light blue, orange red and other colors, but generally it is green. In addition, there are different matrix series and different activators in the self-luminous materials. When they are combined, they will have different luminescent spectral characteristics. The luminescent color is generally determined by the luminescent color of the substrate and the luminescent color of the activator. Therefore, it will lead to different color, intensity and afterglow time. When the matrix and activator emit light together, there will be color superposition. The green light produced by the activator alone is due to the fact that the emission band of the activator is between 500nm and 560nm.

 

At present, most of the research on self-luminous materials has focused on blue-green luminescent materials. At the same time, these inorganic self-luminous materials have been commercialized so that green light is mainly observed in daily life. What is more, the application prospects of self-luminous products in other colors are not clear, so they are almost invisible on the market.

 

Currently, the emission range of self-luminous materials has covered the range from ultraviolet to short-wave infrared. Especially near-infrared and short-wave infrared self-luminous materials, they show great potential in the field of biological imaging and night vision monitoring. What is exciting is that some laboratories have developed a series of excellent near-infrared and short-wave infrared persistence luminescent materials in recent years. The afterglow time can reach hundreds of hours.

 

From the current application status, green and blue self-luminous materials have been widely promoted and applied. They are not only used in safety fire protection and emergency lighting instructions, but also in luminous plastics and luminous coatings. This material requires no electricity and has the characteristics of safety and health. Beyond doubts, it is a very meaningful new energy source and we should devote ourselves to the research and improvement of this self-luminous material.