Adjusting the sodium diffusion into CuInGaSe2 absorbers by preheating of Mo/SLG substrates Original Research Article

We propose a very simple method to adjust the supply of Na from a Mo/soda-lime glass (SLG) substrate into the overgrown CuInGaSe2(CIGS) layer. Mo/SLG substrates for CIGS solar cells were heated in vacuum (=preheated) before use. Na composition in the finished CIGS films were measured by electron probe microanalysis, in association with the preheating temperature and thickness of the Mo layers. The Na concentration at the surface of the CIGS layers decreased with higher preheating temperature, while the cell performance improved.