Vacuum-Healing of Grain Boundaries in Sodium-Doped CuInSe2 Solar Cell Absorbers

Finn Babbe, Nicoleta Nicoara, Harvey Guthrey, Nathalie Valle, Omar Ramirez Sanchez, Damien Aureau, Hossam Elanzeery, Deepanjan Sharma, Jose Virtuoso, Jean-Nicolas Audinot, Anastasiya Zelenina, Sevan Gharabeiki, Tom Wirtz, Susanne Siebentritt, Phillip Dale, Sascha Sadewasser, Diego Colombara

Research output: Contribution to journalArticlepeer-review

4 Scopus Citations

Abstract

Alkali metal doping and grain boundaries (GB) have been at the center of attention within the Cu(In,Ga)(S,Se)2 photovoltaics community for years. This study provides the first experimental evidence that the GB of sodium-doped CuInSe2 thin films may undertake reversible oxidation even at room temperature, whereas undoped films may not. The findings are corroborated by cathodoluminescence imaging, secondary ion mass spectrometry, and Kelvin probe force microscopy on air-exposed films subsequently subject to vacuum. A thermochemical assessment identifies the likely solid–gas equilibria involved. These reactions open new research questions with respect to the beneficial role played by alkali metal dopants in chalcopyrite solar cells and may steer the community toward new breakthroughs.

Original languageAmerican English
Article number2204183
Number of pages11
JournalAdvanced Energy Materials
Volume13
Issue number17
DOIs
StatePublished - 2023

Bibliographical note

Publisher Copyright:
© 2023 The Authors. Advanced Energy Materials published by Wiley-VCH GmbH.

NREL Publication Number

  • NREL/JA-5K00-85809

Keywords

  • alkali metal post-deposition treatment
  • Cu(In,Ga)Se
  • electrostatic potential fluctuations
  • grain boundaries
  • photovoltaics

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