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Comparative study of water and ammonia rinsing processes of potassium fluoride-treated Cu(In,Ga)Se 2 thin film solar cells

2017; Institute of Physics; Volume: 56; Issue: 8S2 Linguagem: Inglês

10.7567/jjap.56.08mc12

1347-4065

Ishwor Khatri, Kosuke Shudo, Junpei Matsuura, Mutsumi Sugiyama, Tokio Nakada,

Copper-based nanomaterials and applications

In this work, potassium fluoride (KF)-treated Cu(In,Ga)Se2 (CIGS) thin films were rinsed in ammonia and water solutions before buffer layer (CdS) deposition and the effects of rinsing on photovoltaic properties were investigated. X-ray photoelectron spectroscopy (XPS) and secondary ion mass spectrometry (SIMS) measurements revealed that sodium atoms out-diffused at the surface region during KF deposition. Water and ammonia rinsing processes of KF-treated CIGS thin films reduced alkali metals from the surface. However, sodium at the Cu-depleted surface layer remained at a high concentration, suggesting the occupation of Cu vacancies with sodium atoms. On the other hand, ammonia rinsing removed the Cu-poor region from the surfaces of KF-treated CIGS thin films affecting the growth (or nucleation) of the CdS layer. The surface coverage of the CdS layer deposited on the ammonia-rinsed KF-treated CIGS thin film was inferior to than that of water-rinsed samples, resulting in the poor cell performance due to an increased interface recombination.