Organic solar panels now efficient enough to rival silicon models

In short Simplifying... In short Organic solar panels, made from carbon-based materials, are now nearly as efficient as their silicon counterparts, thanks to a new class of materials called non-fullerene acceptors (NFAs).

Researchers discovered that under certain conditions, these NFAs can gain energy from their surroundings, a phenomenon driven by a mix of thermodynamics and quantum mechanics.

This breakthrough could make organic solar panels a more affordable and adaptable choice for future green buildings. Was a long read? Making it simpler... Next Article Next Article

Organic semiconductors are cost-effective and more flexible

Organic solar panels now efficient enough to rival silicon models

By Dwaipayan Roy 01:48 pm Jul 14, 202401:48 pm

What's the story Researchers at the University of Kansas have made a significant advancement in organic semiconductors, suggesting a future where solar cells could be more efficient and versatile. For years, silicon has been the primary material for solar energy capture due to its efficiency and durability. However, these silicon-based solar cells are rigid and expensive to produce, restricting their use on curved surfaces.

Versatile solution

Organic semiconductors: A cost-effective, flexible alternative

Organic semiconductors, carbon-based materials, present a more affordable and adaptable alternative to silicon. "They can potentially lower the production cost for solar panels because these materials can be coated on arbitrary surfaces using solution-based methods — just like how we paint a wall," said Wai-Lun Chan, an associate professor at the university. These unique characteristics make organic solar panels suitable for usage in next-generation green and sustainable buildings.

Efficiency boost

Organic solar cells close efficiency gap with silicon

Despite their advantages, organic solar cells have historically struggled to match the efficiency of silicon-based cells. Silicon panels can convert up to 25% of sunshine into electricity, while organic cells have typically hovered around 12% efficiency. However, recent developments with non-fullerene acceptors (NFAs), a new class of materials, have raised organic solar cell efficiency closer to 20%, challenging the dominance of silicon in the field.

Unusual phenomenon

Researchers discover energy gain in NFAs

The Kansas research team found that under certain conditions, excited electrons in NFAs can receive energy from their surroundings, instead of losing it. "This observation is counterintuitive because excited electrons typically lose their energy to the environment like a cup of hot coffee losing its heat to the surrounding," Chan explained. The team used time-resolved two-photon photoemission spectroscopy, to track the energy of excited electrons to less than a trillionth of a second.

Behavior

Quantum mechanics and thermodynamics drive energy gain

Researchers estimate this energy gain is a result of a combination of thermodynamics and quantum mechanics, where excited electrons appear to exist on multiple molecules simultaneously. "For organic molecules arranged in a specific nanoscale structure, the typical direction of the heat flow is reversed for the total entropy to increase," explained Kushal Rijal, a research team member. This reversed heat flow allows neutral excitons to gain heat from the environment and dissociate into positive and negative charges, producing electrical current.