Researchers from Barcelona-based Institut de Ciències Fotòniques (ICFO) have developed a solar cell design that could potentially increase single-junction solar cell efficiency to nearly 43%.

When  solar panels convert sunlight to electricity, most of the energy is lost along the way as heat and light. According to the Shockley-Queisser limit, standard single-layer solar cells can only reach a 33% conversion rate. Researchers identified Boltzmann losses as one reason for this limit.

To overcome this efficiency limit, researchers replaced the conventional indium tin oxide transparent front electrode with an ultrathin silver layer. The silver layer allows most incoming light to pass through while conducting electricity and partially reflecting light.

By restricting the angles through which photons are emitted, the design reduces Boltzmann losses and improves the cell’s ability to convert sunlight into electricity.

However, the study demonstrated only small experimental efficiency gains in tests. The researchers estimate that further development of the approach could theoretically enable efficiencies approaching 43%.

The approach builds on previous attempts to use optical confinement in solar cells.

One approach involves tandem solar cells, which combine materials with different bandgaps to absorb a broader portion of the solar spectrum. Chinese solar manufacturer LONGi earlier reported a 35.5% efficiency record using a perovskite-silicon tandem solar cell.

Researchers at Kyushu University and Johannes Gutenberg University Mainz have separately reported a quantum yield of 130% using singlet fission.

Last year, researchers at the University of New South Wales (UNSW), Sydney claimed that they have increased the efficiency of solar technology by utilizing the concept of singlet fission, increasing the theoretical efficiency limit of silicon cells to approximately 45%.

In January this year, researchers at UNSW Sydney set a world record efficiency for solar cells based on antimony chalcogenide, achieving a certified power conversion efficiency of 10.7%.