LONGi Green Energy Technology Co., Ltd. (hereinafter referred to as "LONGi"), a China-based solar technology company, recently published a research paper titled Perovskite-silicon tandem solar cells with bilayer interface passivation online in the journal Nature as the first corresponding author. It reported the research results of breaking through the efficiency limit of single-junction solar cells by developing crystalline silicon-perovskite dual-junction tandem solar cells.

The dual-junction tandem solar cells are considered to have the potential to exceed the theoretical efficiency limit of single-junction solar cells in terms of photovoltaic conversion efficiency. For decades, research institutions and teams worldwide have been committed to achieving this goal. 

In November 2023, LONGi announced that its crystalline silicon-perovskite tandem solar cell has been certified by the National Renewable Energy Laboratory with an efficiency of 33.9 percent. This achievement has set a new world record for the efficiency of this type of cell and surpasses the Shockley-Queisser limit of single-junction semiconductor photovoltaic materials.

The company employed a double-layer staggered passivation strategy, which more effectively suppresses the non-radiative recombination at the perovskite interface while ensuring efficient charge transport. To better achieve structural coupling between the perovskite top cell and the crystalline silicon bottom cell, LONGi has developed a patented technology for silicon heterojunction solar cells with an asymmetric textured surface. The front surface of this silicon cell has a fine textured surface, facilitating the solution-based preparation of perovskite film, while the rear surface of the silicon cell uses a standard large size textured surface to achieve better passivation and infrared spectral response. 

Making a series of key technological breakthroughs, LONGi's tandem team has achieved a certified conversion efficiency record of 33.9 percent for ultra-high-efficiency perovskite/crystalline silicon tandem solar cells. This is the first time that the efficiency of tandem solar cells has been experimentally proven to exceed the Shockley-Queisser efficiency limit of single junction solar cells, marking a milestone achievement.

The work also received strong support and assistance from the co-corresponding agencies, including Soochow University, Clean Energy Research Institute of China Huaneng, and the Hong Kong Polytechnic University. 

In recent years, LONGi has maintained intensive R&D activities in the field of crystalline silicon-perovskite tandem solar cells, continuously achieving breakthrough progresses. Currently, the two-terminal tandem prototype devices (1 square centimeter) developed by LONGi's tandem team have been authoritatively certified with a record efficiency of 34.6 percent. The commercial-sized two-terminal tandem cells developed for mass production and the world's first square meter four-terminal tandem modules have been certified with efficiencies of 30.1 percent and 25.8 percent, respectively. These results demonstrate a significant efficiency advantage over single junction silicon cell technology. This achievement has greatly boosted the global photovoltaic industry's confidence and expectations for the next generation of ultra-high-efficiency tandem photovoltaic power generation technology.