Low-Cd CIGS solar cells made with a hybrid CdS/Zn(O,S) buffer layer

Journal Article · Thu Oct 27 00:00:00 EDT 2016 · IEEE Journal of Photovoltaics

DOI:https://doi.org/10.1109/JPHOTOV.2016.2617041· OSTI ID:1357746

Garris, Rebekah L. ^[1]; Mansfield, Lorelle M. ^[1]; Egaas, Brian ^[1]; Ramanathan, Kannan ^[1]

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1. National Renewable Energy Lab. (NREL), Golden, CO (United States)

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. As a result, 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.

• Research Organization: National Renewable Energy Lab. (NREL), Golden, CO (United States)
• Sponsoring Organization: USDOE Office of Energy Efficiency and Renewable Energy (EERE)
• Grant/Contract Number: AC36-08GO28308
• OSTI ID: 1357746
• Report Number(s): NREL/JA-5K00-66614
• Journal Information: IEEE Journal of Photovoltaics, Vol. 7, Issue 1; ISSN 2156-3381
• Publisher: IEEE
• Country of Publication: United States
• Language: English

Related Subjects

14 SOLAR ENERGY
alternative buffer layer
Cd-free
CdS
Cu(In
Ga)Se2 (CIGS)
low-Cd
thin-film photovoltaic
Zn(O
S)