The future of solar energy is perovskite cells. Scientists have found a way to fully recycle them.

Silicon Panels Replaced by Perovskite

Scientists from Sweden's Linköping University have developed a way to repeatedly recycle all parts of solar cells without using environmentally harmful solvents. Moreover, the new cells made from recycled perovskite are as efficient as the original cells, and the recycling process is based on a non-toxic water-based solvent.

Silicon-based solar panels have been on the market for over thirty years, and in the context of increasing global electricity consumption, including due to the development of artificial intelligence and the electrification of transport, solar energy is expected to play an increasingly important role in supply.

However, first-generation silicon solar panels are gradually reaching the end of their life cycle, creating and potentially creating huge volumes of waste.

"Currently, there is no effective technology for managing waste from silicon panels, and discarded solar panels end up in landfills, creating piles of electronic waste that cannot be dealt with," says co-author of the study Xun Xiao, who works at the Department of Physics, Chemistry, and Biology at Linköping University.

Therefore, scientific research is increasingly focused on the development of new types of solar cells that would take into account the requirements for recycling after their end of life. One of the most promising new generation solar cells are modules made from a mineral called perovskite.

Focused on the End of the Life Cycle

The production of photovoltaic cells from perovskite is relatively cheap and the production process is quite simple. The resulting products are characterized by being light, flexible, and transparent, which allows them to be installed on various surfaces, such as windows.

Perovskite cells are also highly efficient – they can convert up to 25% of solar energy into electricity, which is comparable to conventional silicon solar cells. However, these cells have a shorter lifespan than silicon solar cells, so it is important that their recycling is efficient and environmentally friendly.

"There are many companies that are already trying to bring perovskite solar cells to the market, but we would like to avoid further waste accumulation. Therefore, as part of our project, we have developed a method that allows all parts of photovoltaics to be reused to produce a new perovskite solar cell without affecting the performance of the new cell," says co-author of the study Niansheng Xu.

Perovskite solar cells also contain a certain amount of lead, which makes the photovoltaic element highly efficient, but also places increased demands on the efficient recycling process of the cells when they are no longer in use.

Several methods for dismantling perovskite solar cells have already been developed, with most of them featuring a substance called dimethylformamide, which is a common component of paint solvents. However, it is also a toxic substance that is dangerous to the environment and potentially carcinogenic.

They Regain the Vast Majority of Material

Perovskite photovoltaics are usually disposed of in parts, or decomposed into individual layers, using other substances such as chlorobenzene or methylamine, in addition to dimethylformamide. Although this recycling process is functional, the fact that it depends on hazardous substances is problematic in terms of environmental burden and industrial operation.

The contribution of Swedish researchers lies in the fact that, within the technology they are presenting, water is used as a solvent in the dismantling of end-of-life perovskites, and, most importantly, new recycled high-quality perovskites can be produced from the aqueous solution.

"We can recycle everything – cover glasses, electrodes, perovskite layers, and also the layer that serves to transfer charge," says Xun Xiao.

At the beginning of the process, the scientists apply heat to the waste modules. They heat them to a temperature of 150 °C for three minutes to soften the encapsulating material ethylene vinyl acetate, which facilitates the separation of layers. The ecological recycling process then consists of immersing the used solar cells in an aqueous solution, from which the scientists can recover up to 99% of high-quality perovskite crystals.

In addition to water, the solution contains several inexpensive additives, such as sodium acetate (NaOAc), sodium iodide (NaI), and phosphorous acid (H3PO2).

The authors of the research claim that their recycling strategy significantly reduces the environmental burden associated with perovskite solar modules compared to landfilling, especially in terms of toxicity to human health and impacts associated with the use of natural resources, and also reduces the price of electricity.

In the continuation of the research, the scientists want to scale up the method to an industrial level. Their study was published in the prestigious scientific journal Nature.

Source: www.energie-portal.sk