Diffusional investigation of alkali ions from composition tuned glass substrates to Mo-thin film for solar cell application

Abstract Na-diffusion from soda lime glass (SLG) substrate to overlayers is found to enhance the performance of CuInGaS2/CuZnSnS4 based thin film solar cells. In the present work, the diffusion mechanism of alkali ions (Li, K along with Na) from specially designed glass substrates, other than SLG, to the direct current magnetron sputtered (dc-MS) Molybdenum (Mo) thin film are investigated. The alkali diffusion kinetics was studied using secondary ion mass spectroscopy in terms of lattice and grain boundary diffusion. The substrate composition is found to be critically influence the diffusion and segregation parameters. Moreover, higher Na diffusion is observed from the synthesized glass to Mo-thin film in comparison to the commercially available soda lime glass (SLG) substrate at different annealing conditions.