Low-Cd CIGS Solar Cells Made With a Hybrid CdS/Zn(O,S) Buffer Layer

Rebekah Garris, Lorelle Mansfield, Brian Egaas, Kannan Ramanathan

Research output: Contribution to journalArticlepeer-review

21 Scopus Citations


In Cu(In,Ga)Se2 (CIGS) solar cells, CdS and Zn(O,S) buffer layers were compared with a hybrid buffer layer consisting of thin CdS followed Zn(O,S). We explore the physics of this hybrid layer that combines the standard (Cd) approach with the alternative (Zn) approach in the pursuit to unlock further potential for CIGS technology. CdS buffer development has shown optimal interface properties, whereas Zn(O,S) buffer development has shown increased photocurrent. Although a totally Cd-free solar module is more marketable, the retention of a small amount of Cd can be beneficial to achieve optimum junction properties. As long as the amount of Cd is reduced to less than 0.01% by weight, the presence of Cd does not violate the hazardous substance restrictions of the European Union (EU). We estimate the amount of Cd allowed in the EU for CIGS on both glass and stainless steel substrates, and we show that reducing Cd becomes increasingly important as substrate weights decrease. This hybrid buffer layer had reduced Cd content and a wider space charge region, while achieving equal or better solar cell performance than buffer layers of either CdS or Zn(O,S) alone.

Original languageAmerican English
Article number7723862
Pages (from-to)281-285
Number of pages5
JournalIEEE Journal of Photovoltaics
Issue number1
StatePublished - Jan 2017

Bibliographical note

Publisher Copyright:
© 2016 IEEE.

NREL Publication Number

  • NREL/JA-5K00-66614


  • Alternative buffer layer
  • Cd-free
  • CdS
  • Cu(In,Ga)Se (CIGS)
  • low-Cd
  • thin-film photovoltaic (PV)
  • Zn(O,S)


Dive into the research topics of 'Low-Cd CIGS Solar Cells Made With a Hybrid CdS/Zn(O,S) Buffer Layer'. Together they form a unique fingerprint.

Cite this