Pb in halide perovskites for photovoltaics: Reasons for optimism

Following the achievement of impressive power conversion efficiencies of perovskite solar cells (PSCs), the current challenges of this technology include long-term stability, upscaling for industrial processing, and its environmental effect. One of the significant concerns of the latter is accidental Pb leaching from PSCs and modules, due to the well-documented Pb toxicity. Such concerns may cause deceleration in PSC commercialization. However, this threat is found to be comparable to that posed by currently used Pb-containing products, and a plethora of measures are available to mitigate the environmental impact of Pb, as we present in this review. We show that the amount of Pb is estimated to be comparable to that in currently used electricity generation technologies, including fossil fuels, electronic solder wires, and lead-acid batteries. Analysis of accidental (worst-case) scenarios shows that the released quantities are within the orders-of-magnitude typical of currently used Pb-containing technologies. By comparison, PSC processing is found to have larger environmental impacts than Pb release, and the currently available Pb substituents, such as Sn, also have significant negative environmental impacts. Pb contamination can effectively be reduced and controlled using Pb adsorbing materials implemented into the encapsulation layers or integrated into the PSC. Recycling and reusing Pb-containing materials will also reduce the environmental impact, increase the material availability and decrease the devices' energy payback time. We, therefore, suggest that Pb in PSCs and its effect on the environment are not as concerning as they seem to be.