Berlin 2012 – wissenschaftliches Programm
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MM: Fachverband Metall- und Materialphysik
MM 41: Topical Session Modern Atom Probe Tomography II - Functional Materials
MM 41.2: Vortrag
Mittwoch, 28. März 2012, 17:00–17:15, H 0107
Exploring the internal interfaces at the atomic-scale in Cu(In,Ga)Se2 thin-films solar cells — •Oana Cojocaru-Mirédin1, Pyuck-Pa Choi1, Roland Wuerz2, and Dierk Raabe1 — 1Max-Planck-Institut für Eisenforschung, Max-Planck-Str. 1, 40237 Düsseldorf, Germany — 2Zentrum für Sonnenenergie- und Wasserstoff-Forschung Baden-Württemberg, Stuttgart, Germany
Cu(In,Ga)Se2 solar cells possess a high efficiency, despite the polycrystalline structure of the absorber layer. This is mainly due not only to the impurities diffusion from the soda-lime glass substrate inside the absorber layer, but also to the CdS/Cu(In,Ga)Se2 p-n junction. However, the recombination mechanism between the defects and the impurities at the internal interfaces remains far to be understood. This is due to a lack of information on local chemical changes across the internal interfaces at the nanoscale. In this work, the internal interfaces, CdS/Cu(In,Ga)Se2 interface and Cu(In,Ga)Se2 grain boundaries, were explored at atomic-scale by means of atom probe tomography. A Cu-depleted and Cd-doped region (~ 2 nm in width) was detected at the Cu(In,Ga)Se2 surface. It was also shown that Cd diffused through the Cu(In,Ga)Se2 grain boundaries during the deposition of CdS layer. The diffusion of Cd inside the Cu(In,Ga)Se2 grain, but also in the grain boundaries prove the existence of a buried p-n homojunction within the Cu(In,Ga)Se2 absorber layer. Regarding the Na (K) and O impurities, they were found to decorate not only the CdS/Cu(In,Ga)Se2 interface, but also the Cu(In,Ga)Se2 grain boundaries. The present results were compared with the existing electronic GB models.