Making a Perovskite Photovoltaic Cell from Scratch – pv magazine International

August 14, 2024 Valerie Thompson

Scientists at the U.S. Department of Energy’s National Renewable Energy Laboratory (NREL) used a circular economy framework to determine how to scale, deploy, and design future metal halide perovskite solar panels so they can be easily recycled.

With ongoing initiatives to commercialize metal halide perovskite (MHP) solar technology underway, particularly efforts to ensure sustained performance in the field, NREL scientists have initiated a study of sustainability design factors as another important aspect of commercialization.

“Our goal with this perspective paper was to point out that existing technology does not prioritize building products with sustainability and circularity in mind. It has not been designed specifically to minimize waste or use the lowest energy processing steps,” said Joey Luther, corresponding author of the study pv magazine“However, because PV is an inherently sustainable technology, it is time to start assessing how we can advance the commercialization of MHP with sustainability in mind.”

The group conducted the evaluation based on a prototype single-junction MHP module similar to commercial designs, mounted on mounting rails in a glass-glass module configuration with polymer encapsulants and edge sealing typical of silicon and cadmium telluride panels. Individual PV cells are integrated by etching and include a front glass covered with a transparent conductor, an MHP layer sandwiched between electron and hole transport materials, and a rear electrode.

In addition, the team took a closer look at the chemical components, molecules, and materials typically used in A, B, and X perovskites.

Taking all the above aspects into account, sustainability aspects such as: energy intensity of production, carbon intensity, extraction of rare minerals, recyclability, abundance of resources on Earth, costs, origin of fossil fuels, reliable containment, health hazards and flammability were assessed.

The prototype was further evaluated based on critical material issues, embodied energy, carbon footprint, and closed-loop supply chain processes. The analysis included frame, rail materials, front and back glass, encapsulating polymers, solvents, electron and hole transport materials, and electrode materials.

In a richly informative table, the team details how the eleven “Rs” of circularity for photovoltaics can offer opportunities and benefits within sustainable production. Adapting the concept of “reduce, reuse, recycle”, some of the Rs discussed are listed here: rejecting fossil fuels and high-carbon materials; reducing energy, materials and carbon inputs; repairing or designing for repair, reuse, repowering, restoring and recovering energy.

When it comes to recycling, the researchers noted that “recycling” includes both downcycling to lower-value or lower-quality products. They explained that recycling is beneficial when recovered raw materials replace virgin materials that require energy-intensive refining. There is room for improvement. For example, PV glass production still uses virgin sources in new PV glass products, rather than post-consumer PV glass cullet, they noted.

The team identified five key areas and opportunities to pursue. First, improving the reliability of the MHP module to meet current commercial PV lifespan standards. Second, investigating the supply chain of low-volume raw materials, such as cesium, and ensuring adequate availability for sustainable scaling of a given MHP composition or focusing research on reduction or substitution. Third, exploring alternatives to indium. Fourth, investigating how to accelerate PV glass recycling without downcycling. And fifth, further improving module remanufacturing processes.

“A sensible combination of these solutions would enable MHP-PV cells to make a significant and sustainable contribution to the energy transition,” the team stressed.

The researchers said that “circularizing the PV supply chain, particularly through recycling and remanufacturing of glass,” offers opportunities to reduce the embodied energy and carbon of MHP-PV. “Improving the lifetime and reliability remains central to the energy transition and provides the greatest benefits,” they concluded.

This perspective is presented in detail in the article “Sustainable Pathways for Perovskite Photovoltaics” published by natural materials.

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