Longi HIBC's research results on flexible silicon-based tandem cells were published in two papers in Nature within three days, a consecutive appearance in this top international journal.
Recently, two breakthrough research achievements of LONGi Green Energy were successively published in the authoritative academic journal Nature, comprehensively showcasing the company's latest progress in the field of cutting - edge technologies.
On November 10, 2025, Nature published online an important progress made by the research team of LONGi Green Energy in collaboration with Soochow University, Xi'an Jiaotong University and other institutions in the research direction of silicon - based tandem solar cells. The efficiency of the small - area device of the ultra - thin crystalline silicon - perovskite tandem solar cell developed by the team was certified by the National Renewable Energy Laboratory (NREL) of the United States to reach 33.4%, and the efficiency of the commercial - size flexible tandem solar cell on silicon wafers was certified by the Fraunhofer Institute for Solar Energy Systems (Fraunhofer ISE) in Germany to reach 29.8%. It is reported that this is the world's first and only world record for the efficiency of flexible crystalline silicon - perovskite tandem solar cells certified by an international authoritative organization. This breakthrough progress has laid a solid foundation for the commercial development of flexible silicon - based tandem solar cells in lightweight/flexible high - power photovoltaic scenarios such as space photovoltaics and vehicle - mounted photovoltaics.
On November 13, 2025, Nature published online the research results of the amorphous - polycrystalline hybrid back - contact structure (HIBC) solar cell developed by the team of LONGi Green Energy in collaboration with Sun Yat - sen University and Lanzhou University. Previously, on April 11, 2025, LONGi Green Energy announced that its HIBC solar cell had refreshed the world record for the efficiency of single - crystalline silicon solar cells with 27.81%. Based on the BC solar cell platform technology that LONGi has focused on developing, the HIBC solar cell combines the advantages of high - temperature polycrystalline and low - temperature amorphous silicon solar cell technologies, and is the culmination of silicon - based solar cell technologies. Due to the need to be compatible with the characteristics of both high - temperature and low - temperature cell processes in its manufacturing process, the development difficulty is unprecedented. The team achieved a certified efficiency of 27.81% and a fill factor of 87.55% on LONGi's self - developed industrial - grade Tai Rui silicon wafers, both of which set new world records. It is worth noting that the hybrid back - contact structure is a new high - efficiency solar cell technology pioneered and verified by a Chinese team, with complete independent intellectual property rights and extremely high technical barriers. The laser - induced local crystallization technology and in - situ edge passivation technology developed by the team have the advantage of being compatible with existing production lines, which greatly promotes the high - quality industrialization of mass - produced silicon solar cells with higher efficiency and lower cost. According to the latest progress, the modules based on HIBC solar cells have now reached a conversion efficiency of 25.9% and an output power of 700 W (2.7 - square - meter format).
Previously, in October 2024, Nature published back - to - back (2024, 635, p596–603 and p604–609) two research achievements of the team, namely the record - breaking HBC and silicon - based tandem solar cells. This time, Nature once again successively published two breakthrough R & D achievements of the company, demonstrating LONGi Green Energy's determination and strength to lead the industry development through technological innovation and combat inefficient involution.
R & D Achievement 1: The conversion efficiency of crystalline silicon hybrid back - contact structure solar cells exceeds 27.81%
By placing all the N - type and P - type contact areas and electrodes on the back of the solar cell, the back - contact structure solar cell minimizes the shading loss on the front side, and is an inevitable choice for continuous improvement of the conversion efficiency of crystalline silicon photovoltaics. However, limited by core challenges such as the difficulty in simultaneously meeting the passivation performance and contact resistance indicators of the P - type contact area, the difficulty in balancing the longitudinal carrier transport and lateral leakage current, and the existence of recombination and leakage in the edge area, the potential of this high - efficiency cell structure is severely restricted. To address the above three aspects of problems, the team innovatively developed an amorphous - polycrystalline hybrid back - contact structure (HIBC) solar cell that integrates laser - induced crystallization and in - situ edge passivation.
There are three main innovation points:
(1) An amorphous silicon contact with a low - temperature process is used in the P - type area, and a polycrystalline silicon contact with a high - temperature process is used in the N - type area, respectively constructing excellent P - type and N - type passivated contacts;
(2) To solve the problem of poor vertical conductivity of the P - type amorphous silicon contact layer, a laser - induced local crystallization technology was developed. Only the sub - micron - scale area at the pyramid tip is converted into nanocrystalline silicon, which significantly reduces the contact resistivity in the vertical direction, while the original amorphous silicon film layer in other areas maintains the small lateral leakage current performance in the polarity overlapping area;
(3) An in - situ edge passivation technology was developed. During the cell manufacturing process, a firm passivation layer is simultaneously formed on the vulnerable cutting edges, effectively suppressing the carrier recombination in the edge area. Based on the excellent full - passivation surface and electrical performance of the device, the research team further constructed a new physical model that correlates the ideality factor of the diode with the carrier loss mechanism, quantitatively describing the influence of different recombination mechanisms on the ideality factor, and clarifying the principle of the restriction of bulk recombination and surface recombination on the fill factor, providing clear theoretical guidance for the design of high - performance solar cells.
R & D Achievement 2: Lightweight and flexible perovskite - crystalline silicon tandem device with full - silicon - wafer size
The perovskite/crystalline silicon tandem solar cell technology significantly boosts the theoretical efficiency by integrating the advantages of two semiconductor materials, and is recognized as a new - generation disruptive photovoltaic technology. The traditional perception is that single - crystalline silicon is a rigid and brittle material. However, the atomic structure of silicon has a certain elastic deformation ability. When the thickness of the silicon wafer is reduced to dozens of microns (the thickness of traditional silicon wafers is usually about 120 - 200 microns), even if the bending radius is less than 2 cm, the surface stress of the silicon wafer is still lower than its intrinsic fracture threshold, and no cracks will occur. Therefore, ultra - thin silicon wafers can meet the deformation requirements of lightweight and flexible devices. However, the interface of the perovskite functional layer is prone to delamination and failure under repeated bending and temperature changes, resulting in a greatly reduced service life.
To solve this problem, the team adopted an innovatively optimized process structure design to construct a double - layer buffer layer design of loose and dense layers. The carefully designed loose SnOx layer can absorb and dissipate strain energy like a spring mattress, effectively relieving the mechanical stress caused by ion bombardment during the preparation process and deformation during subsequent use; while the dense SnOx layer can ensure efficient interface charge extraction and stable electrical connection.
This double - layer structure design precisely resolves the conflicting requirements of stress buffering and efficient transmission at the micro - and nano - scale, ensuring that the tandem device has excellent bending resistance while being compatible with excellent power generation capacity. The team achieved a power conversion efficiency of nearly 30% on an ultra - thin full - silicon - wafer tandem device with a thickness of only 60 microns. The ultra - thin tandem device can be folded in half, with a bending radius of 1.5 cm, a weight of less than 4.4 grams, and a specific power of up to 1.77 W/g. In the laboratory on a small - size device, the team also achieved an internationally - certified conversion efficiency record of 33.4%. The research work fully demonstrates the superiority of this tandem solar cell structure in terms of efficiency and bending fatigue resistance, as well as its future application potential.