Sustainability in Perovskite Solar Cells.

At a current value of 25.5%, perovskites have reached some of the highest power conversion efficiencies of all single-junction solar cell devices. Researchers, however, are questioning their readiness for the commercial market, citing reasons of the toxicity of the lead-based active layer and instability. Closer examination of the life cycle of perovskite solar cells reveals that there are more areas than just these which should be addressed in order to bring an environmentally friendly and sustainable technology to global use. In this review, we discuss these issues. Life cycle analyses show that high temperature processes, heavy use of organic solvents, and extensive use of certain materials can have high up and downstream consequences in terms of emissions, human and ecotoxicity. We further bring attention to the toxicity of the perovskites themselves, where the most direct analyses suggest that the lead cannot be considered totally safe, despite its small quantity and that replacements such as tin may be more toxic in certain scenarios. As a way to reduce the negative environmental impact, we highlight ways in which researchers have used encapsulation and recycling to extend the life of the entire unit and its components and to prevent lead leakage. We hope this review directs researchers toward new strategies to introduce a clean solar technology to the world.