Insight into Metastable Defects in Flexible \text{Cu}(\text{In}_{1-x}\text{Ga}_{x})\text{Se}_{2} Modules via X-ray Microscopy

Tara Nietzold, Michael E. Stuckelberger, Trumann Walker, Jeff Bailey, Dmitry Poplavskyy, Rouin Farshchi, Barry Lai, Mariana I. Bertoni

Research output: Chapter in Book/Report/Conference proceedingConference contribution


The origin of metastability in \text{Cu}(\text{In}_{1-x}\text{Ga}_{x})\text{Se}_{2} solar cells has long be a topic of study and debate. The drop in device performance after light soaking has been attributed to changes in the VSe-VCu defect pair and to the electromigration of Cu. In this work, we use a suite of X-ray microscopy tools to study the nanoscale distribution of Cu and Se in industrially-relevant CIGS modules on stainless steel before and after accelerated stress testing from dark heat and light soaking. Changes in chemical inhomogeneity are studied through nano-scale X-ray fluorescence and correlated to electrical performance through Xray beam induced current and voltage. We observe no meaningful variation in the Cu distribution before and after light soaking but a sensible difference in the Se distribution. Average XBIC values at the nano-scale trend directly with changes in full device J_{\text{sc}} both of which see a reduction after light soaking. We note that low performing areas of XBIC in both the initial and dark heat samples perform significantly worse after light soaking when compared to changes in the good performing areas.

Original languageEnglish (US)
Title of host publication2020 47th IEEE Photovoltaic Specialists Conference, PVSC 2020
PublisherInstitute of Electrical and Electronics Engineers Inc.
Number of pages5
ISBN (Electronic)9781728161150
StatePublished - Jun 14 2020
Event47th IEEE Photovoltaic Specialists Conference, PVSC 2020 - Calgary, Canada
Duration: Jun 15 2020Aug 21 2020

Publication series

NameConference Record of the IEEE Photovoltaic Specialists Conference
ISSN (Print)0160-8371


Conference47th IEEE Photovoltaic Specialists Conference, PVSC 2020


  • CIGS
  • X-ray beam induced current
  • X-ray fluorescence
  • dark heat
  • defects
  • light soaking
  • selenization
  • {Cu}({In}_{1-x}{Ga}_{x})\text{Se}_{2}

ASJC Scopus subject areas

  • Control and Systems Engineering
  • Industrial and Manufacturing Engineering
  • Electrical and Electronic Engineering


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