A research team from Hebei University of Science and Technology in China and the RIKEN Advanced Photonics Center in Japan has developed a new laser microwelding technology for transparent and rigid materials, targeting applications in solar cell encapsulation. This process, based on a silver ion solution, is claimed to achieve high-quality connections.
The researchers demonstrated the process's strength in glass encapsulation, using a sample containing a solar cell chip. The welded glass encapsulation remained functional underwater.
Glass-to-glass welding is one of several edge sealing methods used in solar photovoltaic device encapsulation. Along with novel adhesives, it is believed to contribute to improving the durability and cost reduction of photovoltaic modules. It is also a key technological direction for increasing the recycling efficiency of solar panels.
Femtosecond lasers, an infrared laser that emits extremely short single laser pulses, are currently widely used in ophthalmic procedures such as cataract surgery.
In a paper titled "Microwelding of Transparent Rigid Solar Cell Encapsulation Using Femtosecond Laser Photochemical Reduction of Silver Ion Solution," the researchers note that a high-quality connection scheme for photovoltaic encapsulation materials is crucial. Their proposed silver ion solution provides an intermediate layer for the weld, enabling femtosecond laser microwelding of glass and dissimilar materials.
Experimental results showed that photochemically reduced silver nanoclusters in solution increased the shear strength of glass to 27.36 MPa at a low input energy density (2.4 J/cm²). The research team stated that the silver ion solution not only improved energy utilization efficiency but also suppressed weld crack formation, enhancing the applicability of liquid-layer-assisted femtosecond laser welding.
The researchers also conducted welding experiments on single-crystalline silicon and sapphire, materials representing semiconductor and optical materials with significantly different thermophysical properties. "Despite these differences in material properties, femtosecond laser welding successfully achieved heterojunction connections," the team stated.
The experimental samples included commercial silica glass (20 × 20 × 1 mm), sapphire glass (20 × 20 × 1 mm), and single-crystalline silicon (10 × 10 × 0.33 mm). The laser system used in the experiments was a Pharos PH2-20W system.
The team then tested the sealing properties of the encapsulated silicon solar cell chip. The photovoltaic device used a quartz glass substrate and conductive tape electrodes, placed in water. To facilitate electrical signal monitoring, the top interface of the package structure was intentionally left unwelded.
The researchers noted, "The encapsulated solar cell chip maintained electrical conductivity while submerged in water. This demonstrates that the silver ion solution-assisted femtosecond laser welding process can achieve high-strength connections and effectively mitigate the effects of moisture and other extreme environmental factors on solar device performance."
The reliability of this method was further verified through thermal shock and water-tightness tests, which showed that it met the IPX7 waterproof rating and IEC 60529:2013 standards.
A research team from Hebei University of Science and Technology in China and the RIKEN Advanced Photonics Center in Japan has developed a new laser microwelding technology for transparent and rigid materials, targeting applications in solar cell encapsulation. This process, based on a silver ion solution, is claimed to achieve high-quality connections.
The researchers demonstrated the process's strength in glass encapsulation, using a sample containing a solar cell chip. The welded glass encapsulation remained functional underwater.
Glass-to-glass welding is one of several edge sealing methods used in solar photovoltaic device encapsulation. Along with novel adhesives, it is believed to contribute to improving the durability and cost reduction of photovoltaic modules. It is also a key technological direction for increasing the recycling efficiency of solar panels.
Femtosecond lasers, an infrared laser that emits extremely short single laser pulses, are currently widely used in ophthalmic procedures such as cataract surgery.
In a paper titled "Microwelding of Transparent Rigid Solar Cell Encapsulation Using Femtosecond Laser Photochemical Reduction of Silver Ion Solution," the researchers note that a high-quality connection scheme for photovoltaic encapsulation materials is crucial. Their proposed silver ion solution provides an intermediate layer for the weld, enabling femtosecond laser microwelding of glass and dissimilar materials.
Experimental results showed that photochemically reduced silver nanoclusters in solution increased the shear strength of glass to 27.36 MPa at a low input energy density (2.4 J/cm²). The research team stated that the silver ion solution not only improved energy utilization efficiency but also suppressed weld crack formation, enhancing the applicability of liquid-layer-assisted femtosecond laser welding.
The researchers also conducted welding experiments on single-crystalline silicon and sapphire, materials representing semiconductor and optical materials with significantly different thermophysical properties. "Despite these differences in material properties, femtosecond laser welding successfully achieved heterojunction connections," the team stated.
The experimental samples included commercial silica glass (20 × 20 × 1 mm), sapphire glass (20 × 20 × 1 mm), and single-crystalline silicon (10 × 10 × 0.33 mm). The laser system used in the experiments was a Pharos PH2-20W system.
The team then tested the sealing properties of the encapsulated silicon solar cell chip. The photovoltaic device used a quartz glass substrate and conductive tape electrodes, placed in water. To facilitate electrical signal monitoring, the top interface of the package structure was intentionally left unwelded.
The researchers noted, "The encapsulated solar cell chip maintained electrical conductivity while submerged in water. This demonstrates that the silver ion solution-assisted femtosecond laser welding process can achieve high-strength connections and effectively mitigate the effects of moisture and other extreme environmental factors on solar device performance."
The reliability of this method was further verified through thermal shock and water-tightness tests, which showed that it met the IPX7 waterproof rating and IEC 60529:2013 standards.
