Lumerical Tutorial : Making a 2D infinite periodic array. 

I would like to say, Thank you for your clear and understandable presentation about 2D infinite periodic array using FDTD simulation. If you are interested lets ask one very important and delouse question: How can we simulate plasmonic inverted organic solar cells usingFDTD i.e, 200nm thickness of Al; 50nm thickness of PEDOT:PSS; 100nm thickness of P3HT:PCBM (Active layer) ; 20nm ZnO (spacer); 180nm thickness of ITO & square array of 60nm Ag coated by 5nm thickness of silica on the ZnO?

Brother i cannot change shape in XY plane why?