Break the world record! The efficiency of photovoltaic cells is close to 30%, not far from the theoretical upper limit.

SMM: Silicon has been the dominant player in the solar cell market for decades, but in recent years it has been gradually buried by "rising stars" perovskite, whose efficiency has risen rapidly from less than 4% in 2009 to 20% earlier this year, close to the long-term record of 25% silicon. Today, however, engineers have developed a series solar cell made of perovskite and silicon with an efficiency of 29.15%, breaking the world record.

Moreover, another major feature of this new perovskite / silicon series battery is that it can maintain stable performance without package protection after continuous exposure to air and simulated sunlight for more than 300 hours. It is reported that the team used a complex perovskite composition with a 1.68ev band gap and focused on optimizing the substrate interface.

It is understood that compared with a single cell used alone, solar cells composed of two semiconductors with different bandgaps can achieve quite high efficiency when used in series. This is because series cells make more efficient use of the solar spectrum.

In fact, the series design of silicon and perovskite performed well as early as five years ago, when its highest efficiency reached 13.7%, 25.2% two years ago and 27.7% earlier this year. The series battery efficiency developed by scientists at the Helmholtz Joint Research Centre (Helmholtz Zentrum M ü nchen in Munich is close to a record 30 per cent and is not far from the theoretical limit of 35 per cent.

Earlier this year, this efficiency record was certified at the Fraunhofer Institute of Solar Systems ((Fraunhofer Institute for Solar Energy Systems)) and included in the NREL chart, which has been documenting advances in solar cell technology since 1976. The results were also published recently in the scientific journal Science.

"29.15% efficiency is not only a record of this technology, but also at the top of the entire emerging photovoltaic category in the NREL chart," said Eike K ö hnen, lead author of the study and a doctoral student on the Albrecht team.

For now, the tandem solar cell was tested in an one-square-centimeter sample, but the researchers say it should be relatively simple to expand it to a more realistic size.