Taking sustainability further with organic solar cells

The UK government aims to increase solar capacity by nearly fivefold to 70GW by 2035 as part of wider plans to power up Britain with cleaner, cheaper and more secure energy sources. Although traditional silicon-based solar panels have paved the way for a cleaner future, there is a pressing need to address their environmental impact, particularly when it comes to end-of-life disposal and waste generation.

Taking sustainability further with organic solar cells

Here, Professor Franky So, Chief Technology Officer at solar technology specialist NextGen Nano, discusses the role organic solar cells (OSCs) can play in addressing the issue of solar panel waste.

According to Statista, widespread adoption of solar panel technology started in the early 2000s and has been increasing exponentially every year. With the average usable lifespan of solar panels being 25 to 30 years, we can soon expect to see a sharp increase in the number of panels needing to be replaced and recycled.

However, the BBC article – Challenge to stop solar panels becoming a ‘waste mountain’ – published in June 2023, highlighted the lack of recycling facilities specifically designed to process solar panels mainly due to the fact there has not been much waste to process until now. In fact, the world’s first facility dedicated to this opened in June 2023.

A rapidly growing problem

In the article, Ute Collier, deputy director of the International Renewable Energy Agency states that: “By 2030, we think we’re going to have four million tonnes of scrap – which is still manageable – but by 2050, we could end up with more than 200 million tonnes globally.”

Traditional solar panels, particularly those based on crystalline silicon, pose challenges when it comes to recycling. Their complex structure, composed of multiple layers including silicon wafers, glass, metal conductors and encapsulants, requires specialised, energy-intensive processes to disassemble and separate materials. Additionally, some components, like lead and cadmium in soldering materials, are hazardous, demanding careful handling during recycling.

So, what can we do to make solar technology more sustainable from the start?

Making solar power organic

Organic solar cells are made from carbon-rich (organic) compounds, as opposed to the silicon in traditional solar panels. Their structure consists of a flexible and transparent substrate as the base, topped with a transparent conductive electrode to allow sunlight to enter.

The active layer absorbs sunlight and generates electron-hole pairs. On top of the active layer is the hole transport layer, which transports holes to the transparent electrode, and below is the electron transport layer, responsible for moving electrons to the bottom electrode. The bottom electrode collects the electrons, completing the electrical circuit.

The organic polymers that make up OSCs can be designed with recyclability in mind. Some of these organic materials can be broken down and reprocessed, enabling the recovery of valuable components. Additionally, the solution-based manufacturing processes used for OSCs, such as printing or coating, allow for the deposition of thin layers on flexible substrates. This characteristic makes it easier to separate and recycle different layers.

Due to this structure, OSCs can be compatible with existing recycling methods developed for plastic films and other flexible materials. However, it is important to note that the recyclability of OSCs is still an active area of research and development, with specific recycling technologies and infrastructure for them not yet fully established.

Currently, OSCs have lower efficiencies compared to inorganic cells, which generally range from between 15 and 25 per cent.

Ongoing research, like that conducted at NextGen Nano, aims to improve efficiency and stability. Pairing the benefits of organic cells with efficiencies that are comparable to traditional solar cells will facilitate their adoption, bringing a more environmentally friendly and recyclable solar power solution to the market while reducing future waste issues.

A deliberate positive environmental impact

NextGen Nano’s OSC technology replaces the rigid and opaque silicon substrates of traditional solar panels with thin, lightweight, and tuneable substrates based on fluorine-doped tin oxide (FTO). This shift empowers OSCs with versatile functionalities, allowing them to be integrated into nearly all surfaces, from windows, walls, car roofs and even portable electronics.

The company’s organic solar cells have attracted significant attention for photovoltaic (PV) applications due to their special merits of intrinsic flexibility, lightweight, high throughput large-area printing, and low-cost and non-toxic raw materials.

NextGen Nano’s mission is the efficient creation and use of energy whilst reducing all reliance on pollutants and finite materials, and thus having a deliberate positive environmental impact.

The company has three main divisions: organic solar, organic displays and superfluorescence for quantum computing.

Find out more here: https://nextgen-nano.co.uk

About the author

Dr. Franky So is a highly accomplished researcher with over 80 patents and 160 peer-reviewed articles.

He is renowned for his editorial roles in prestigious journals and his distinguished career, which includes leadership at Motorola and a current position as the Walter and Ida Freeman Distinguished Professor at North Carolina State University.