Interface Formation between CdS and Alkali Postdeposition-Treated Cu(In,Ga)Se2 Thin-Film Solar Cell Absorbers - Key to Understanding the Efficiency Gain

Yang P, Wilks RG, Yang W, Bär M (2020)

Publication Type: Journal article

Publication year: 2020

Journal

ACS Applied Materials and Interfaces American Chemical Society

DOI: 10.1021/acsami.9b20327

Abstract

A combination of X-ray photoelectron/Auger electron spectroscopy and soft X-ray emission spectroscopy has been employed to investigate the impact of different alkali postdeposition treatments (PDTs) on the chemical structure of the (buried) CdS/Cu(In,Ga)Se2 heterojunction: the key interface in chalcopyrite-based thin-film solar cells. Chemical bath deposited (CBD) CdS layers of different thicknesses on NaF PDT (CIGSe^NaF) and NaF + KF PDT (CIGSe^NaF+KF) Cu(In,Ga)Se2 absorbers prepared at low temperature (to facilitate the use of flexible, e.g., polyimide, substrates) were studied. While we find the CdS/CIGSe^NaF interface to be mainly free of significant chemical interaction, in the proximity of the CdS/CIGSe^NaF+KF interface, an elemental redistribution involving Cd, In, K, S, and Se is revealed. For the early stages of the CBD-CdS process, our findings are in agreement with the conversion of the K-In-Se-type layer present on the CIGSe^NaF+KF surface into a mixed Cd-In-(O,OH,S,Se)-type layer, probably having some Cd-In and (S,O)-Se composition gradients. For long CBD times - independent of employed PDT - we find the buffer material to be best described by a Cd(O,OH,S)-like species rather than by a pure CdS buffer. These findings shed light on the observed performance leap of corresponding CdS/CIGSe^NaF+KF-based solar cells.

Authors with CRIS profile

Marcus Bär Professur für Röntgenspektroskopie (HIERN)

Involved external institutions

Helmholtz-Zentrum Berlin für Materialien und Energie (HZB)

Germany (DE) Lawrence Berkeley National Laboratory (LBNL)

United States (USA) (US)

How to cite

APA:

Yang, P., Wilks, R.G., Yang, W., & Bär, M. (2020). Interface Formation between CdS and Alkali Postdeposition-Treated Cu(In,Ga)Se2 Thin-Film Solar Cell Absorbers - Key to Understanding the Efficiency Gain. ACS Applied Materials and Interfaces. https://doi.org/10.1021/acsami.9b20327

MLA:

Yang, Penghui, et al. "Interface Formation between CdS and Alkali Postdeposition-Treated Cu(In,Ga)Se2 Thin-Film Solar Cell Absorbers - Key to Understanding the Efficiency Gain." ACS Applied Materials and Interfaces (2020).

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