Thin-Film Photovoltaic Cells: Long-Term Metal(loid) Leaching at Their End-of-Life

Abstract

The photovoltaic effect of thin-film copper indium gallium selenide cells (CIGS) is conferred by the latter elements. Organic photovoltaic cells (OPV), relying on organic light-absorbing molecules, also contain a variety of metals (e.g., Zn, Al, In, Sn, Ag). The environmental impact of such technologies is largely unknown, in particular when the physical integrity deteriorates upon end-of-life, possibly facilitating cell constituent leaching. This study analyzed long-term inorganic leaching from damaged OPV and CIGS into different model waters. Leachate concentrations were put into perspective by calculating the predicted environmental concentrations (PEC) for several scenarios. Roof-top acidic rain runoff from CIGS was found to be the predominant emission source for metals and metalloids, with Cd released to such extents that PEC (173.4 μg Cd L(-1)) would considerably exceed acute toxicity concentrations for Daphnia magna . Other PEC for CIGS (9.9 mg Mo L(-1) and 9.4 μg Se L(-1)) were in the range of teratogenic effects. In contrast, OPV released little metals with calculated PEC being below even conservative drinking water guidelines. Time-resolved single-particle ICP-MS indicated that some metals (Zn, Mo, Ag) were in nanoparticulate form, raising nanotoxicity concerns. Leaching kinetics called for revision of existing standardized (accelerated) leaching protocols because long-term release was most relevant.

Implications for current regulatory waste toxicity characterisation methods from analysing metal and metalloid leaching from photovoltaic modules

“…In addition to the previous criticisms of the regulatory methods, Zimmermann et al investigated the long-term leaching of thin-film PV cells using natural waters and showed that due to long-term releases of metals and metalloids from CIGS cells, leaching procedures need revision to account for the long-term releases (Zimmermann et al 2013). The current study expands the scope of the previous study to investigate leaching using regulatory methods in the USA and includes PV cells and modules.…”

“…In a previous study, natural waters were used to benchmark metal and metalloid leaching from CIGS and organic PV cells with an aim to derive predicted environmental concentrations for scenarios of roof-top acidic rain, marine, and surface water environments (Zimmermann et al 2013). This previous study did not consider the applicability of current regulatory methods to PV waste as considered in this study.…”

Redox-stat bioreactors for elucidating mobilisation mechanisms of trace elements: an example of As-contaminated mining soils

“…The concentration of total dissolved As, Mn and Fe were quantified on an Agilent 7500cx ICP-MS (Agilent Technologies AG, Basel, Switzerland) with standard settings (Zimmermann et al 2013) at masses 56 Fe, 55 Mn and 75 As. Mn and As were measured in the collision mode using helium, whereas Fe was measured in the reaction mode using H 2 .…”

Outdoor fate and environmental impact of polymer solar cells through leaching and emission to rainwater and soil

“…First (direct) experimental evidence points to OPV releasing minor amounts of metals to the environment in comparison to other thin film technologies in laboratory studies. 9 However, direct evidence of such release in actual outdoor installations is completely lacking today. In particular, impaired physical integrity may result in the increased release of cell materials.…”