What are the benefits of reduced grain size in window material in solar cells, in regard to optical properties? Is there any possible disadvantage of it?
Reduced grain size increases toughness, strength of a material. Smaller grains offer enhanced ratios of surface area (A) to volume (V) i.e., greater ratio of grain boundary (GB) to dislocations. The more the GBs, the higher is the strength because nano-grain size of thin film produces more GBs between crystal grains. In addition, nano-scale materials have far larger surface areas than similar masses of larger-scale materials. As surface area per mass of a material increases, a greater amount of the material can come into contact with surrounding materials, thus affecting reactivity. Nanostructured window material can exhibit more uniformity. Besides these structural advantages, which optical improvements can be achieved through reducing grain size in solar cell window material? And, how?
Md. Mahabub Alam Moon You are right that Optical improvements of solar cell windows depends on the grain sizes. There are major optical effects these can affect the performance of a solar cell due to the cell's window grain size such as optical waveguiding and scattering. The grain size within a window does change light propagating direction due to multiple reflections, which could guide more lights into the cell and reduce the scattering. This enhances more absorbed light for the active layer of the cell, thereby improving the efficiency of a cell.
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