Comparative Life Cycle Toxicity Assessment of Perovskite/Silicon Tandem Photovoltaics

Abstract

Perovskite/silicon tandem solar cells (PSTs) have emerged as promising photovoltaic (PV) technology that can exceed the theoretical power conversion efficiency limit of single-junction solar cells. To determine the future potential benefits of PSTs, it is crucial to accurately assess their environmental impacts and recyclability. Here, we present the first complete life cycle toxicity assessment of the PST panels. For this, we evaluated the toxicity of material procurement, manufacturing, and use stages and compared them with the toxicity of crystalline silicon PVs and CdTe PVs, as well as other electricity sources. For the end-of-life (EoL) stage, we developed three variants of panel recycling processes and compared their toxicity impacts with those of procuring the materials required to manufacture a new panel. We found that the life cycle toxicity of PV sin general is mainly driven by metal emissions. PSTs in particular emit more metals (and these are more toxic) than other PVs, but less than conventional sources of energy. A lower silver content─or more sustainable silver procurement─would be the first step toward making PSTs more environmentally sustainable. Concerning the EoL analysis, all proposed variants are less impactful than materials procured from the market. Their largest benefits can be found in the recovery of the bottom glass and crystalline silicon subcell, the copper cables, and the top glass.