Scientists make eco-friendly organic solar cells from wood

Kraft lignin improves the stability in organic solar cells thanks to its ability to form hydrogen bonds that acts as a sort of glue. Credit: Thor Balkhed.

Researchers at Linköping University and the Royal Institute of Technology (KTH) in Sweden have made a significant leap in the world of renewable energy.

They’ve discovered a way to use wood, one of nature’s most abundant materials, to create eco-friendly and efficient solar cells.

This groundbreaking research was published in the prestigious journal Advanced Materials.

Sunlight is a key sustainable energy source, but the traditional solar cells, which are usually made from silicon, are not only costly but also complicated to manufacture.

This process can even lead to environmental hazards due to chemical spills. That’s why scientists are turning their attention to organic solar cells.

These are not only cheaper and lighter but also flexible, making them perfect for various uses, such as powering gadgets on clothing or for indoor applications.

Although organic solar cells are a step forward, they have their drawbacks. Most are made from plastics or polymers derived from oil. So, despite being organic, they’re not as green as they could be.

The team from Linköping University and KTH has developed an organic solar cell using a wood-based material called kraft lignin, which is sourced directly from wood pulp.

Currently, lignin is only used in a small part of the solar cell, specifically in the electron transport layer connected to the cathode. But the ultimate goal is to create a solar cell almost entirely from wood materials.

Why Wood?

Professor Mats Fahlman from the Laboratory of Organic Electronics at Linköping University explains, “Our aim is to create efficient, reliable, and environmentally friendly solar cells at a low cost.

This study is a first step towards replacing today’s oil-based materials with wood-based alternatives.”

The researchers have used an unaltered form of lignin, known as kraft lignin, taken directly from the paper manufacturing process.

They found that this form of lignin helps stabilize the solar cell due to its ability to create numerous hydrogen bonds.

Qilun Zhang, a principal research engineer at the university, points out that the use of kraft lignin in the solar cells not only makes them more stable but also more environmentally friendly. This innovation could lead to a significant shift in how solar cells are produced and used.

Organic solar cells are already being used, mainly in indoor settings and to power low-energy devices like sensors.

This discovery is an essential first step in bringing organic solar cells into the market. With further development, this technology could be scaled up for broader applications, like powering homes and businesses.

Organic solar cells might not be the most efficient, but their non-toxic, sustainable, and cost-effective nature gives them a significant edge. As Professor Fahlman states, “If these solar cells achieve a 15%–20% efficiency rate, that would be more than sufficient for most applications.”

This innovative research paves the way for a more sustainable and environmentally friendly future in solar energy, harnessing the power of one of our most common natural resources: wood.