In the production process of solar cells, silicon wafers, as core components, play a decisive role in the performance of solar cells. Diamond powder, with its unique physical properties, has become a key material in optimizing cell performance and improving photoelectric conversion efficiency in the cutting and surface treatment of solar cell silicon wafers.

I. Cutting silicon ingots into wafers

1. 1. Cutting equipment and tools
   • (1) The equipment used to cut silicon ingots into wafers is usually a high-precision multi-wire saw. This equipment is equipped with special cutting wires, which are generally high-strength steel wires coated or inlaid with diamond powder. The particle size of diamond powder is generally between 5 and 20 microns, depending on actual production needs.
   • (2) Driven by the multi-wire saw, the cutting wire reciprocates at a very high speed while applying a certain pressure to the silicon ingot. Due to the highest hardness in nature (Mohs hardness 10), the diamond powder inlaid on the cutting wire is like countless tiny and sharp cutting edges.
2. 2. Cutting process and advantages
   • (1) When the cutting wire with diamond powder contacts the silicon ingot, the powder quickly cuts into the silicon ingot, cutting the ingot into thin slices layer by layer according to the preset thickness. During the entire cutting process, the high hardness and wear resistance of the diamond powder ensure that the cutting wire always maintains good cutting ability.
   • (2) Taking the common cutting of single-crystal silicon ingots as an example, this diamond powder-assisted cutting method can control the thickness tolerance of the silicon wafer within a very small range, generally reaching ±20 microns. Moreover, the surface of the cut silicon wafer is relatively smooth, reducing the workload of subsequent surface treatment. At the same time, the high-efficiency cutting effect of diamond powder improves production efficiency and reduces the production cost of silicon wafers.

II. Silicon wafer surface texturing

1. 1. Purpose and principle of texturing
   • (1) The main purpose of surface texturing of solar cell silicon wafers is to increase light absorption efficiency. When light shines on the surface of the silicon wafer, the smooth surface is prone to reflection, resulting in partial loss of light energy. By forming a specific microstructure (such as a pyramid structure) on the surface of the silicon wafer, the light can be reflected and refracted multiple times on the surface of the silicon wafer, extending the propagation path of light in the silicon wafer, thereby increasing the probability of light absorption.
   • (2) The texturing process usually uses a combination of chemical etching and mechanical polishing, in which diamond powder plays an important role in mechanical polishing.
2. 2. The grinding effect of diamond powder
   • (1) In the texturing process, the silicon wafer is first immersed in a specific chemical etchant to cause a chemical reaction on the surface of the silicon wafer, forming a preliminary microscopic rough structure. Then, the surface of the silicon wafer is further treated using a polishing slurry containing diamond powder.
   • (2) The particle size of diamond powder is generally between 1 and 5 microns. After mixing with a special polishing liquid, it acts uniformly on the surface of the silicon wafer under the drive of polishing equipment. These tiny diamond particles, with their hardness and sharp edges, finely polish the microscopic convex parts on the surface of the silicon wafer.
   • (3) After diamond powder polishing, the microstructure of the silicon wafer surface is more regular and uniform, and the size and shape of the pyramid structure are more in line with the optical design requirements. For example, the average height of the pyramid structure can be controlled between 1 and 3 microns, and the apex angle is close to the ideal 54.7°. This precisely controlled microstructure can greatly improve light absorption efficiency. Studies have shown that the light absorption efficiency of silicon wafers after diamond powder polishing can be increased by 10% to 15% compared to before treatment.
3. 3. Impact on the conversion efficiency of solar cells
   • (1) Due to the improvement of light absorption efficiency on the surface of the silicon wafer, more light energy can be converted into electrical energy. In the overall operation process of solar cells, the number of photogenerated carriers increases, thereby increasing the short-circuit current density of solar cells. At the same time, a good surface microstructure also helps reduce surface recombination and improve open-circuit voltage.
   • (2) Considering these factors, the photoelectric conversion efficiency of solar cells after surface treatment with diamond powder is significantly improved. In actual production, the conversion efficiency of solar cells processed with this process can be improved by 1-2 percentage points. This can greatly improve power generation efficiency and reduce power generation costs for large-scale solar power generation applications, which has important economic and environmental benefits.