im working now on TPV solar cells and metamaterials and i realy need our help in CST microwave i have a tpv cell simulation and i want to extract particullarly the absorbtion of only the active layer ( cell composed of multiple layers) how i can do that; and also i want to know how to extract the short current density of the cell based on optical properties (basically same question) thanks in advance

You need to know the absorption coefficients of the coefficient of every material in the material stack. You can also get the absorption coefficient given the extinction coefficient. You need to know also the characteristic wave impedance z0 of these materials.

Then you can make ray tracing through this sack where you can calculate the reflectance and the absorbance in each layer.

Knowing the absorbance you can calculate the generation rate of the electro hole pairs. Hence you can get the collected photocurrent from each layer. By summing all these partial photocurrents you can get the overall photo current.

You can proceed similar to the book chapter:Chapter Solar cells and arrays: Principles, analysis and design

You need to know the absorption coefficients of the coefficient of every material in the material stack. You can also get the absorption coefficient given the extinction coefficient. You need to know also the characteristic wave impedance z0 of these materials.

Then you can make ray tracing through this sack where you can calculate the reflectance and the absorbance in each layer.

Knowing the absorbance you can calculate the generation rate of the electro hole pairs. Hence you can get the collected photocurrent from each layer. By summing all these partial photocurrents you can get the overall photo current.

You can proceed similar to the book chapter:Chapter Solar cells and arrays: Principles, analysis and design