Texturization control for fabrication of high efficiency mono crystalline si solar cell
We studied the texturization mechanism of mono crystalline silicon wafer using some alternative additives. We successfully controlled the texture size with change of concentration of KOH in the etchant. We also proposed one appropriate model of role of additives in texturization process. In our proposed mechanism, the additives should play a role as micro-mask when the micro pyramid is formed and the texturization process should be dominated by the correlation of etching rate and adhesion and desorption rate of additives. We also fabricated solar cells with several texture sizes and evaluated them. The decrease of F.F. with the decrease of texture size was mainly caused by the increase of Rs and this result suggested that we had to optimize the screen printing and firing conditions for the small texture. In addition, there are thick damaged layer on the top and bottom of texture, and these damaged layer cause the deterioration of cell efficiency with texture miniaturization. Reduction of the damage is important to realize high efficiency solar cell using miniaturized texture.
A simple and cost-effective approach for fabricating pyramids on crystalline silicon wafers
A simple and cost-effective approach for texturing crystalline silicon wafers is proposed. The advantage over conventional texturization processes is the fact that no surfactant is added in alkaline etchants. Hydrogen bubbles, regarded as residuals in conventional texturization processes, are utilized in this approach as etch masks on a silicon surface. This is accomplished by placing a metal grid with suitable openings on silicon wafers to confine the hydrogen bubbles created during etching. Pyramids with a size ranging from 6 to 9 μm are uniformly fabricated using this method. Without antireflection coating, an average weighted reflectance of 15.1% is achieved.
Ray-trace simulation of light trapping in silicon solar cell with texture structures
Abstract We investigated the light trapping effect in a solar cell. We performed ray-tracing simulation for a light trapping structure in a silicon crystalline solar cell. By comparing theoretical and experimental values, the reliability of a simulation technique was evaluated. Using this simulation technique, we evaluated the light trapping effect in the silicon crystalline solar cell and glass with a V-shaped texture. Furthermore, we investigated the light trapping effect in a silicon thin film solar cell. In a silicon thin film with a thickness of 20 μm deposited on V-shaped glass, reflectivity which is comparable to that in a pyramidal texture structure was obtained. We concluded that the simulation technique used in this work is very effective for optimization of the structure in the enhancement of the light trapping effect.