As governments push towards greener energy, solar power use has surged. Now breakthroughs in material science, cell design, and recycling are reshaping its future, one molecule at a time.
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Photovoltaics 101
Photovoltaic technology works by changing sunlight into electricity via the photovoltaic (PV) effect. When a photon of light hits a semiconductor material, say silicon, electrons are released.
Each PV cell consists of n-type and p-type semiconductors that form a p-n junction, allowing for the directional flow of electrons and holes when exposed to light. To boost efficiency, manufacturers apply an anti-reflective coating (ARC) that minimizes optical losses by preventing light from bouncing off the cell’s surface.2
The Challenges Associated With PV Technology
Solar energy has a green reputation, but they have some less than eco-friendly faults. When it comes to manufacturing and end-of-life disposal, PV cells need some work.
First, the mining and processing of the raw materials used to create solar panels disrupt ecosystems. Transporting these resources adds to greenhouse gas emissions. And then, after their lifespan, disposing of PV panels is just as problematic. Improper recycling or disposal leads to the release of cadmium and lead, which are severely toxic to living organisms.3
Recycling is extra tricky because of the different types of manufacturing of PV panels. There is no single recycling method to apply to all the different types of solar panels, and the approaches we do have are expensive, often exceeding the financial cost of the recovered raw materials.4 This has made it impossible to upscale PV panels recycling strategies to deal with the vast amount of PV panels that have completed their operational cycles.
Finally, first-generation monocrystalline and polycrystalline cells are efficient but expensive and heat-sensitive. Second-generation designs reduced material use but often relied on toxic components, sacrificing environmental performance for cost.5 In response, researchers are pushing toward next-generation materials and scalable recycling technologies.
Novel Absorber Glues for Highly Efficient Bifacial PVs
Bifacial PVs are gaining popularity due to their ability to harness reflected light.
Traditionally, transparent conducting oxides (TCOs) are applied to the rear surface via radio-frequency magnetron sputtering, a process that can damage key functional layers of the PV cells.
A recent study proposed an alternative: molten selenium (Se) as a “glue” to bond charge-transport layers onto fluorine-doped tin oxide glass, bypassing the need for sputtering altogether.6
The researchers used this glue to develop bifacial solar cells using titanium dioxide (TiO2) on the front and molybdenum oxide (MoOx) on the rear. Under standard AM1.5G sunlight at 100 mW/cm2, the front side achieved a power conversion efficiency (PCE) of 6.54 %, and the rear 5.89 %, with a bifaciality of 90.1 %. This is a record for inorganic thin-film cells.
Efficiency under standard sunlight with an albedo of 0.3 reached 8.61 %, while under indoor lighting (1000 lux, albedo 0.8), the cells delivered a striking 26.17 % efficiency, outperforming both commercial amorphous silicon and all lead-free perovskite cells tested to date.
Novel Rubidium–Lead-Bromide Hybrid Perovskite PV Cells
Hybrid perovskite solar cells have also seen an uptake in recent years. They're prized for their high light absorption, low defect density, and excellent charge mobility.
Inorganic RbPbBr3 is a major candidate for advancing the development of PV cells due to its outstanding electrical and optical properties. The integration of efficient electron transport layers (ETLs), which is the insertion of elemental ions into the RbPbBr3 lattice, significantly boosts the efficiency of the resulting solar cells.
In a recent study, researchers designed, analyzed, and optimized RbPbBr3-based hybrid PV cells integrated with different chalcogenide ETLs of In2S3, WS2, and SnS2. The researchers designed a solar cell incorporating a p-type absorber layer, a heavily doped n-type ETL (mentioned above), with an FTO window layer and a gold back electrode.
Among these variants, the cell using SnS2 as the ETL achieved the highest PCE of 29.75 % and a fill factor (FF) of 87.91%. Meanwhile, the cells with In2S3 and WS2 as ETLs reached PCEs of 21.15 % and 24.57 %, respectively.
However, performance dropped as temperatures rose. At elevated working conditions, the SnS2-based cell’s PCE decreased from 31.2 % to 23.9 %, likely due to increased random motion of charge carriers. Even so, these hybrid cells represent a compelling option for future industrial deployment.7
Advancements in PV Recycling
Researchers are working to find ways to deal with solar panel waste. One such innovation involves deep eutectic solvents with switchable hydrophilicity. These novel solvents can dissolve key PV components such as ethylene–vinyl acetate (EVA) and separate silicon wafers from glass, allowing complete disassembly and reuse.8
Environmentally benign, the dissolved EVA can be recycled by converting the novel solvents into a hydrophilic state. Afterwards, they can be switched back to their original hydrophobic state and reused.8 This efficient material recovery means the solvents are both ecologically safe and highly effective at recycling waste PV cells.
Another promising study involved enzymatic delamination to separate the EVA and Si layers. Experts devised a first-of-its-kind strategy using sunflower oil, which demonstrated a 100 % delamination rate during experimental trials. Even better, this novel biotechnology is energy efficient and doesn't produce toxic byproducts.9
Despite these advances, large-scale recycling remains limited by the lack of unified regulatory standards. As Sim et al. point out, standardized testing protocols and policy frameworks are essential for industrial-scale implementation and circular PV economies.10
Looking Ahead
From molten selenium adhesives to bio-based recycling solvents, photovoltaics are entering a new era defined by material innovation and ecological responsibility. Machine learning and other digital tools are expected to accelerate the design of these high-performance, low-impact systems.
With sustained investment and harmonised regulation, solar power is on track to become the front-runner in modern sustainable green energy generation in the next five years.
Further Reading
- International Energy Agency, IEA (2024). Solar PV. Renewable Energy System. [Online]. Available at: https://www.iea.org/energy-system/renewables/solar-pv [Accessed on: August 04, 2025].
- Sharma, P. et. al. (2025) Comprehensive study on photovoltaic cell's generation and factors affecting its performance: A Review. Mater Renew Sustain Energy. 14. 21. Available at: https://doi.org/10.1007/s40243-024-00292-5
- Lakhouit, A. et. al. (2025). Assessing the Environmental Impact of PV Emissions and Sustainability Challenges. Sustainability. 17. 2842. Available at: https://doi.org/10.3390/su17072842
- Cui, H. et al. (2022) Technoeconomic analysis of high-value, crystalline silicon photovoltaic module recycling processes. Sol. Energy Mater. Sol. Cell 238. 111592–111597. Available at: https://doi.org/10.1016/j.solmat.2022.111592
- Nagaraja, M. et. al. (2025). Advancements and challenges in solar photovoltaic technologies: enhancing technical performance for sustainable clean energy–A review. Solar Energy Advances, 5, 100084. Available at: https://doi.org/10.1016/j.seja.2024.100084
- An, X. et. al. (2025). Photovoltaic Absorber “Glues” for Efficient Bifacial Selenium Photovoltaics. Angewandte Chemie, e202505297. Available at: https://doi.org/10.1002/ange.202505297
- Reza, M. et. al. (2024). Design and optimization of high-performance novel RbPbBr3-based solar cells with wide-band-gap S-chalcogenide electron transport layers (ETLs). ACS omega. 9(18). 19824-19836. Available at: https://doi.org/10.1021/acsomega.3c08285
- Yang, B. et. al. (2024). Hydrophobic deep eutectic solvents as novel media for the recycling of waste photovoltaic modules. Chemical Engineering Journal. 498. 155011. Available at: https://doi.org/10.1016/j.cej.2024.155011
- Karagöz, S. et. al. (2025). A novel enzymatic delamination method for sustainable recycling of crystal silicon photovoltaic (c-Si PV) modules. Separation and Purification Technology. 361. 131373. Available at: https://doi.org/10.1016/j.seppur.2024.131373
- Sim, Y. et. al. (2025). Open challenges and opportunities in photovoltaic recycling. Nature Reviews Electrical Engineering, 2(2), 96-109. Available at: https://doi.org/10.1038/s44287-024-00124-8
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