“The difficulty is equivalent to putting a thin layer of plastic wrap on a standard football field, in order to make it completely flat and intact, requires a high degree of scientific and precise process control.†In the explanation to prepare a high quality Uniform single-layer graphene, and successfully transferred to the flexible PET substrate and the difficulty of other flat substrate surface, Shi Haofei, deputy director of the micro-nano fabrication and system integration research center of the Chongqing Research Institute of the Chinese Academy of Sciences.
The reporter learned from the hospital recently that the researchers have independently developed the preparation method to realize the growth of 15-inch high-quality, uniform single-layer graphene on a copper foil substrate under low-temperature conditions, and successfully transferred it to the complete flexibility. On the PET substrate and other flat substrate surfaces, the size reached the highest level in China; and further, a graphene transparent electrode was applied to a resistive touch screen to prepare a 7-inch graphene touch screen, which has a flexible and high transmittance. No color cast, low cost, etc.
In recent years, graphene has been widely recognized as a new type of flexible transparent electrode material, and has excellent properties of force, heat, light, and electricity. However, to apply graphene to transparent electrodes, the preparation and rapid and efficient transfer of large-area, high-quality graphene are the two key issues that must be resolved first.
It is understood that the methods for preparing graphene so far have mainly micro mechanical peeling methods, SiC pyrolysis epitaxial growth chemical vapor deposition (CVD), chemical redox methods, and the like. Among them, the most promising one is the CVD method. This method requires the catalytic growth of graphene on the metal surface first, and then transferred to a different substrate. However, it needs a high temperature of 1000° C., so it is not suitable for large-scale industrial production applications. Conducive to energy conservation and environmental protection.
Shi Haofei introduced the “key technology of graphene transparent electrode†research conducted by the hospital, expanded the traditional method of graphene production by CVD, and proposed the use of economical and readily available industrial raw materials as effective carbon sources, such as plastics (PMMA and polystyrene). As well as liquid benzene, high-quality graphene is grown at a low temperature of 300 degrees Celsius, and a controlled growth of graphene layers can be achieved to some extent. Compared with the transparent conductive film ITO currently on the market, the transparent electrode of graphene prepared by the hospital has a higher light transmittance of 97.1%. It has a large area, small defects, smooth use, lower power consumption, and more stable performance. Thinner and lighter, the cost is much lower than ITO, and it is expected to lead the revolution in related fields such as touch screens, flexible displays, and solar cells.
Silicon Nitride can also be applied to solar cells. After the silicon nitride film is plated by PECVD, not only can it be used as an anti-reflection film to reduce the reflection of incident light, but also, in the deposition process of the silicon nitride film, hydrogen atoms of the reaction product enter the silicon nitride film and the silicon wafer. It acts as a passivation defect. Here, the silicon nitride nitrogen atomic number ratio is not strictly 4:3, but varies within a certain range depending on the process conditions, and the physical properties of the film corresponding to different atomic ratios are different.
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