Recently, two groundbreaking research achievements from LONGi were consecutively published in Nature, showcasing the company's latest progress in cutting-edge PV technologies.
On November 10, 2025, Nature online published significant progress in silicon-based tandem solar cell research by a team jointly formed by LONGi, Soochow University, Xi'an Jiaotong University, and other institutions. The small-area device efficiency of the team's ultra-thin crystalline silicon-perovskite tandem solar cell reached 33.4%, certified by the National Renewable Energy Laboratory (NREL), USA. The efficiency of the commercial-size, silicon-wafer-level flexible tandem cell reached 29.8%, certified by the Fraunhofer Institute for Solar Energy Systems (Fraunhofer ISE), Germany. This marks the first and only world record efficiency for a flexible crystalline silicon-perovskite tandem solar cell certified by an international authoritative body in the global photovoltaic field. This breakthrough lays a solid foundation for the commercial development of flexible silicon-based tandem cells in lightweight/flexible high-power photovoltaic applications such as space photovoltaics and vehicle -integrated photovoltaics.
On November 13, 2025, Nature online published the research results of the Hybrid Interdigitated Back Contact (HIBC) silicon solar cell developed by a team jointly formed by LONGi, Sun Yat-sen University, and Lanzhou University. Previously, on April 11, 2025, LONGi announced its HIBC solar cell had set a new world record for monocrystalline silicon solar cell efficiency at 27.81%. Based on the BC platform technology that LONGi focuses on developing, the HIBC solar cell combines the advantages of both high-temperature processed polysilicon and low-temperature processed amorphous silicon solar cell technologies, representing a culmination of silicon-based solar cell technologies. Its development is exceptionally challenging as the process must be compatible with both high-temperature and low-temperature cell manufacturing process. The team achieved a certified efficiency of 27.81% and a fill factor of 87.55% on LONGi's self-developed industrial-grade TaiRay silicon wafers, setting new world records for both metrics. It is noteworthy that the hybrid interdigitated back-contact structure is a novel high-efficiency cell technology pioneered and validated by a Chinese team, possessing complete independent intellectual property rights and high technical barriers. The laser-induced localized crystallization technology and the in-situ edge passivation technology developed by the team offer advantages of compatibility with existing production lines, significantly promoting the high-quality industrialization of mass-produced silicon solar cells with higher efficiency and lower cost. According to the latest progress, modules based on HIBC cells have now achieved a conversion efficiency of 25.9% and an output power of 700W (for a 2.7 sqm module type).
Previously, in October 2024, Nature published two record-breaking research achievements (HBC and silicon-based tandem solar cells) by the team back-to-back (2024, 635, p596–603 and p604–609). The consecutive publication of these two new groundbreaking R&D achievements in Nature once again demonstrates LONGi's determination and capability to lead industry development through technological innovation and combat inefficient internal competition.
R&D Achievement 1: Conversion Efficiency of Crystalline Silicon Hybrid Interdigitated Back-Contact Solar Cell Breaks 27.81%
Back-contact solar cell, by placing all N-type and P-type contact areas and electrodes on the rear side of the cell, minimize shading losses on the front side, making them an inevitable choice for continuously pushing the conversion efficiency limits of crystalline silicon photovoltaics. However, core challenges such as the difficulty in simultaneously achieving excellent passivation performance and low contact resistivity in the P-type contact region, balancing vertical carrier transport with lateral leakage current, and mitigating recombination and leakage at the edge regions have severely limited the potential of this high-efficiency cell structure. To address these three major challenges, the team innovatively developed a Hybrid Interdigitated Back-Contact (HIBC) silicon solar cell structure incorporating laser-induced crystallization and in-situ edge passivation.
The main innovations are in three aspects:
(1) Utilizing low-temperature processed amorphous silicon contacts for the P-type regions and high-temperature processed polysilicon contacts for the N-type regions, respectively constructing excellent P-type and N-type passivated contacts;
(2) Addressing the challenge of poor vertical conductivity in the P-type amorphous silicon contact layer, developing a laser-induced localized crystallization technique that transforms only the sub-micron scale areas at the pyramid tips into nanocrystalline silicon. This drastically reduces the vertical contact resistivity while the remaining amorphous silicon layers maintain low lateral leakage current performance in the polarity-overlapped regions;
(3) Developing an in-situ edge passivation technology that simultaneously "coats" the fragile cut edges with a robust passivation layer during the cell manufacturing process, effectively suppressing carrier recombination at the edge regions. Based on the excellent overall passivated surface and electrical performance of the device, the research team further established a new physical model correlating the diode's ideality factor with carrier loss mechanisms. This model quantitatively describes the impact of different recombination mechanisms on the ideality factor and elucidates the constraining principles of bulk and surface recombination on the fill factor, providing clear theoretical guidance for the design of high-performance solar cells.
R&D Achievement 2: Full-Wafer-Scale Flexible Perovskite/Crystalline Silicon Tandem Solar Cells
Perovskite/crystalline silicon tandem solar cell technology, which merges the advantages of two semiconductor materials, significantly pushes the theoretical efficiency limit and is recognized as the next-generation disruptive photovoltaic technology. Conventional wisdom holds that monocrystalline silicon is a rigid and brittle material. However, silicon's atomic structure allows for a certain degree of elastic deformation. When the silicon wafer thickness is reduced to tens of micrometers (traditional wafer thickness is typically around 120-200 μm), even with a bending radius of less than 2 cm, the surface stress on the silicon wafer remains below its intrinsic fracture threshold, preventing crack formation. Thus, ultra-thin silicon wafers can meet the deformation requirements for lightweight, flexible devices. However, the interfaces of perovskite functional layers are highly prone to delamination and failure under repeated bending and temperature changes, significantly reducing their operational lifespan.
To address this challenge, the team adopted an innovatively optimized process and structural design, constructing a double buffer layer consisting of a porous and a dense layer. The meticulously designed porous SnOx layer acts like a spring mattress, absorbing and dissipating strain energy, effectively mitigating mechanical stress caused by ion bombardment during fabrication and subsequent deformation during use. The dense SnOx layer ensures efficient interfacial charge extraction and stable electrical connection.
This double-layer structure design precisely resolves the conflict between the needs for stress buffering and efficient transport at the micro-nano scale. It ensures the tandem device achieves excellent bending durability while maintaining compatible and outstanding power generation capability. The team achieved a power conversion efficiency of nearly 30% on a full-wafer-scale tandem device based on an ultra-thin silicon wafer only 60 μm thickness. The ultra-thin tandem device can be folded, achieving a bending radius of 1.5 cm, weighs less than 4.4 grams, and boasts a power-per-weight ratio as high as 1.77 W/g. Simultaneously, for small-area lab-scale devices, the team achieved a certified world record conversion efficiency of 33.4%. This research fully demonstrates the superiority of this tandem cell structure in terms of both efficiency and bending fatigue resistance, highlighting its significant future application potential.
About LONGi
Founded in 2000, LONGi (Stock code: 601012. SH) is committed to being the world's leading solar technology company, focusing on customer-driven value creation for full scenario energy transformation.
Under its mission of 'making the best of solar energy to build a green world', LONGi has dedicated itself to technology innovation and established several business sectors, covering mono silicon wafers, cells and modules, commercial & industrial distributed solar solutions, green energy solutions, building integrated photovoltaic and hydrogen equipment. As an international company, LONGi's business covers more than 160 countries and regions. Actively practicing its "Solar for Solar" concept, LONGi is accelerating the global transition to sustainable energy and promoting energy equity, enabling more people around the world to access affordable clean energy.