Dynamic Impurity Redistributions in Kesterite Absorbers
Journal article, 2020

Cu2ZnSn(S,Se)4 is a promising nontoxic earth-abundant solar cell absorber. To optimize the thin films for solar cell device performance, postdeposition treatments at temperatures below the crystallization temperature are normally performed, which alter the surface and bulk properties. The polycrystalline thin films contain relatively high concentrations of impurities, such as sodium, oxygen and hydrogen. During the treatments, these impurities migrate and likely agglomerate at lattice defects or interfaces. Herein, impurity redistribution after air annealing for temperatures up to 200 °C and short heavy water treatments are studied. In addition, nonuniformities of the sodium distribution on a nanometer and micrometer scale are characterized by atom probe tomography and secondary ion mass spectrometry, respectively. Sodium and oxygen correlate to a greater extent after heat treatments, supporting strong binding between the two impurities. Redistributions of these impurities occur even at room temperature over longer time periods. Heavy water treatments confirm out-diffusion of sodium with more incorporation of oxygen and hydrogen. It is observed that the increased hydrogen content does not originate from the heavy water. The existence of an “ice-like” layer on top of the Cu2ZnSnS4 layer is proposed.


air annealing





solar cell absorber


Sigbjørn Grini

University of Oslo

Hisham Aboulfadl

Chalmers, Physics, Microstructure Physics

Nils Ross

University of Oslo

Uppsala University

Clas Persson

University of Oslo

Royal Institute of Technology (KTH)

Charlotte Platzer-Björkman

Uppsala University

Mattias Thuvander

Chalmers, Physics, Microstructure Physics

Lasse Vines

University of Oslo

Physica Status Solidi (B): Basic Research

0370-1972 (ISSN) 1521-3951 (eISSN)

Vol. 257 6 2000062

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Sustainable development

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Materials Science

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Materials Chemistry

Other Chemistry Topics

Other Materials Engineering


Chalmers Materials Analysis Laboratory



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