Perovskite Recycling: Is Aqueous-based Recovery The Future Of Photovoltaics?

The rapid development of photovoltaic (PV) technologies has made perovskite solar cells a viable alternative to conventional silicon-based panels, revealed a study. As with any emerging technology, however, waste management and environmental sustainability issues must be resolved before large scale commercialisation is viable. Study presents an aqueous-based recycling strategy designed to make perovskite PVs more sustainable and economically viable for the future, by recovering nearly all of the valuable components from the solar modules. This major advance could revolutionise the renewables field by dramatically reducing resource depletion and environmental damage.

Why Recycling in Solar Technologies is More Urgent than Ever
With the increase in global renewable energy demand, the accumulation of end-of-life PV modules has become one of the most crucial challenges. Traditional silicon-based solar panels have already become a significant source of waste, and without aggressive recycling initiatives, perovskite PVs are in danger of following suit. Perovskite PVs contain lead, along with other potentially dangerous materials, unlike silicon-based modules; this requires effective recycling methods to avoid environmental pollution.

In view of this challenge, an aqueous-based holistic recycling strategy has been developed by researchers, which not only alleviates waste but also restores degraded perovskite raw materials. It enables the simultaneous recovery of nearly all constituent parts including perovskite layers, electron transport layers, hole transport layers, substrates, cover glass and metal electrodes at a high yield.

The Operation of Aqueous-Based Recycling
The Operation of Aqueous-Based Recycling Standard perovskite PV recycling methods rely on hazardous solvents such as methylamine and dimethylformamide (DMF), which cause major problems with industrial compatibility and the environment. The new approach however, uses a green solvent and water as the main medium, along with sodium iodide (NaI), sodium acetate (NaOAc), and hypophosphorous acid (H3PO2). These additions help to keep lead-containing perovskite compounds intact for future use while boosting their solubility. To produce high-quality perovskite crystals, the recycling process involves dipping damaged perovskite layers in a hot water-based solution dissolving the materials, and then cooling the solution. This method ensures minimal material loss while keeping the recovered components functional, with a remarkable 99.0% by weight recycling efficiency.

Environmental and Economic Advantages Putting an effective recycling strategy into action for perovskite PVs has big environmental upsides. The study shows that this approach cuts down resource depletion by 96.6% and human toxicity (cancer-related effects) by 68.8% when you compare it to dumping in landfills. Also, by getting back valuable materials from waste PV modules, the process cuts the need for new raw materials easing the pressure on natural resources. Looking at the money side, the recycling strategy brings down the levelized cost of electricity (LCOE) for perovskite PV systems by a lot. By making it possible to recycle multiple times, the approach makes solar modules last longer cutting overall costs for both home and large-scale uses. The study found that perovskite PVs recycled three times had an 18.8% lower LCOE compared to landfill scenarios making them a better choice for widespread use.

Circular Economy with Perovskite Panels
In the study, researchers, propose a perovskite PV system that integrates energy generation with solar module recycling. In this system, perovskite solar farms continuously generate sustainable and low-cost electricity to fulfil societal energy demands. Once solar modules reach the end of their lifespan, they are recycled to fabricate new perovskite PV modules. "In the recycling process, we start with thermal treatment of the waste modules at 150 °C for 3 min to soften the ethylene vinyl acetate (EVA) encapsulant, facilitating delamination. The delaminated modules are then layer-by-layer recycled to reclaim cover glass, spiro-OMeTAD, perovskite crystal powders and SnO2-coated ITO substrates. These recycled materials are subsequently used in the fabrication of new solar modules, thereby completing a full circular loop for perovskite PVs, sesearchers adds.

Aqueous solution for perovskite recycling
The recycling of the lead-containing perovskite layer constitutes a critical aspect of the sustainable perovskite PV development. We have developed an eco-friendly aqueous solution approach for perovskite recycling (Fig. 1a). Within this solution, we introduce three low-cost additives, sodium acetate (NaOAc), sodium iodide (NaI) and hypophosphorous acid (H3PO2), to address solubility, phase purity and stability challenges in the aqueous-based environment. Notably, water exhibits limited solubility towards lead iodide (about 0.044 g per 100 ml at 20 °C)27, despite its ability to dissolve organic iodide salts such as methylammonium iodide and formamidinium iodide. To enhance lead iodide dissolution in water, we introduce acetate ions that readily coordinate with lead ions, forming highly soluble lead acetate (about 44.31 g per 100 ml at 20 °C)28. This coordinative effect is evident by comparing the 1 H-NMR spectrum of sodium acetate with and without added lead iodide (Fig. 1b), in which a distinct chemical shift in the acetate group indicates their strong interaction with lead ions. We make use of methylammonium lead iodide (MAPbI3) to visualize the efficacy of acetate ions in enhancing perovskite dissolution, to which we add 100 mg of MAPbI3 to 4 ml of pure water (Extended Data Fig. 2). After 10 min, undissolved yellow powder remains, indicating the limited solubility of lead iodide in water. Subsequently, with the introduction of a 500 mg ml-1 sodium acetate into solution, the lead iodide powder dissolves within 10 s of shaking. These results indicate that acetate ions can effectively facilitate perovskite dissolution in water through strong coordination with PbI.

Holistic and multi-round recycling
To realise the recycling for perovskite PVs, they further develop recycling approaches for all valuable components in waste perovskite solar modules.They develop a recycling method to recover the hole-transport material, spiro-OMeTAD, with green solvents, that is, ethyl acetate (EA) and ethanol.

By eliminating impurities and reduction in the recycling process (Supplementary Note 4), the purity of recycled neutral spiro-OMeTAD is measured with high-performance liquid chromatography to be 99.82%, which is close to that of fresh material of 99.84%. The recycling efficiency is assessed by three independent cycles to be 97.8 ± 0.3 wt%. The recycled spiro-OMeTAD exhibits nearly identical conductivity and device efficiency compared with those of fresh materials.

Creating a water-based recycling plan for perovskite solar tech marks a big win for green energy. Tackling the trash problem and lessening harm to our planet, this tactic boosts the green cred of perovskite panels making it easier for everyone to get behind them. As we hustle to switch to neat and tidy energy options clever recycle methods like this one are gonna be super useful in shaping a tough-as-nails solar industry that keeps on trucking without wrecking our home turf.