Alkali Dispersion in (Ag,Cu)(In,Ga)Se2 Thin Film Solar Cells - Insight from Theory and Experiment
Artikel i vetenskaplig tidskrift, 2021

Silver alloying of Cu(In,Ga)Se2 absorbers for thin film photovoltaics offers improvements in open-circuit voltage, especially when combined with optimal alkali-treatments and certain Ga concentrations. The relationship between alkali distribution in the absorber and Ag alloying is investigated here, combining experimental and theoretical studies. Atom probe tomography analysis is implemented to quantify the local composition in grain interiors and at grain boundaries. The Na concentration in the bulk increases up to ∼60 ppm for [Ag]/([Ag] + [Cu]) = 0.2 compared to ∼20 ppm for films without Ag and up to ∼200 ppm for [Ag]/([Ag] + [Cu]) = 1.0. First-principles calculations were employed to evaluate the formation energies of alkali-on-group-I defects (where group-I refers to Ag and Cu) in (Ag,Cu)(In,Ga)Se2 as a function of the Ag and Ga contents. The computational results demonstrate strong agreement with the nanoscale analysis results, revealing a clear trend of increased alkali bulk solubility with the Ag concentration. The present study, therefore, provides a more nuanced understanding of the role of Ag in the enhanced performance of the respective photovoltaic devices.

atom probe



solubility limit

first-principles calculations

density functional theory


Hisham Aboulfadl

Chalmers, Fysik, Mikrostrukturfysik

Kostiantyn V. Sopiha

Uppsala universitet

Jan Keller

Uppsala universitet

Jes Larsen

Uppsala universitet

Jonathan J.S. Scragg

Uppsala universitet

Clas Persson

Kungliga Tekniska Högskolan (KTH)

Universitetet i Oslo

Mattias Thuvander

Chalmers, Fysik, Mikrostrukturfysik

Marika Edoff

Uppsala universitet

ACS Applied Materials & Interfaces

1944-8244 (ISSN) 1944-8252 (eISSN)

Vol. 13 6 7188-7199


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