LAUSR

Abstract We propose herein a methodology to find the upper limit of the chemical potential of an impurity/dopant in ab initio extrinsic point defect studies which takes into account the possible formation of binary and ternary phases containing the extrinsic chemical species. As a test-case, we investigate comprehensively alkali (A) doping in β - In 2 S 3 , a buffer material for CIGS solar cells. Our calculations prove that the migration of alkali from the soda-lime glass substrate to the buffer via the absorber and additionally the chemical bath post-deposition treatment may trigger the decomposition of β - In 2 S 3 into AInS 2 and InS at the grain boundaries.