Investigating dislocations in epitaxial Cu(In,Ga)Se2 absorbers using atom probe tomography

The record conversion efficiency of Cu(In,Ga)Se
2
(CIGS) thin film solar cells with an epitaxial monocrystalline absorber (mono-CIGS) is slightly lower than the cells with a polycrystalline absorber (poly-CIGS). Contrary to the poly-CIGS absorber, the fraction of structural defects in mono-CIGS absorber is strongly reduced. During the epitaxial growth of individual layers only dislocations and few antiphase boundaries are formed. This implies that dislocations might have a certain impact on the power conversion efficiency of cells. Therefore, in the present work dislocations in Na-doped and undoped monoCIGS absorber are characterized by atom probe tomography and compared with the ones investigated previously for poly-CIGS. Implications on cell parameters will be discussed.