Alkali Dispersion in (Ag,Cu)(In,Ga)Se2 Thin Film Solar Cells - Insight from Theory and Experiment
Journal article, 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.

first-principles calculations

atom probe


density functional theory

solubility limit



Hisham Aboulfadl

Chalmers, Physics, Microstructure Physics

Kostiantyn V. Sopiha

Uppsala University

Jan Keller

Uppsala University

Jes Larsen

Uppsala University

Jonathan J.S. Scragg

Uppsala University

Clas Persson

University of Oslo

Royal Institute of Technology (KTH)

Mattias Thuvander

Chalmers, Physics, Microstructure Physics

Marika Edoff

Uppsala University

ACS Applied Materials & Interfaces

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

Vol. 13 6 7188-7199

Driving Forces

Sustainable development

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Materials Science

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Other Chemistry Topics

Other Materials Engineering

Condensed Matter Physics


Chalmers Materials Analysis Laboratory





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