Scientists achieve 20% efficiency in organic solar cells with innovative molecular design

Credit: Unsplash+.

Scientists at Hong Kong Polytechnic University (PolyU) have made a breakthrough in organic solar cell (OSC) technology, achieving an impressive 20% efficiency in converting sunlight into electricity.

This significant advancement was made possible through the development of a new type of molecule called a non-fullerene acceptor (NFA), which has distinct photoelectric properties.

Key requirements for organic solar cells

For organic solar cells to be competitive, the light-absorbing molecules must meet several key requirements. These include:

  • A weak-absorption charge transfer state
  • A high dielectric constant
  • Suitable surface energy
  • Proper crystallinity

Meeting these criteria ensures that the solar cells can efficiently convert sunlight into electricity.

Innovative molecular design

Led by Professor Gang Li, the research team at PolyU designed NFA molecules that provide higher open circuit voltage (Voc) and photovoltage while maintaining structural compatibility.

This design approach enabled the organic solar cells to reach an efficiency of 19.9%. By incorporating these NFA molecules into a specific system called the binary PM6

OSC, the team created a ternary system that achieved even higher Voc and power conversion efficiency, surpassing the 20% mark.

This new system significantly reduces energy loss and enhances efficiency, miscibility, crystallinity, and energy level compatibility. The result is a highly efficient organic solar cell that marks a major milestone in photovoltaics (PV) technology, which is the process of converting light into electricity.

While power conversion efficiency is crucial for practical applications of solar cells, it is also essential to consider other factors such as stability and structural compatibility.

The research team’s novel design integrates interdisciplinary research in new materials, chemistry, and device engineering to achieve high performance.

Professor Li’s research group focuses on three main aspects of OSC technology:

  1. Efficiency: Improving the power conversion efficiency of OSCs.
  2. Stability: Ensuring material and device stability for long-term use.
  3. Novel Applications: Exploring potential uses, such as transparent solar cells, which can be integrated into windows and other surfaces.

Their work paves the way for designing high-performance OSCs that could revolutionize renewable energy technology and lead to more efficient, stable, and versatile solar cells.

This achievement, published in the journal Nature Communications under the title “Rational molecular and device design enables organic cells approaching 20% efficiency,” highlights the potential of organic solar cells to become a major player in the field of renewable energy.