In HJT manufacturing, lasers are being explored for selective applications such as laser-induced annealing and laser sintering
Laser-assisted precision transfer printing enables ultra-fine finger formation in HJT cells, reducing shading losses and silver consumption
BC architectures rely heavily on laser ablation and emerging laser-induced bonding techniques, requiring highly customized, low-damage laser processes for complex rear-side stacks
Beyond TOPCon, laser technologies are also finding targeted applications in HJT and BC solar cell architectures, where specific process challenges create opportunities for selective, high-precision laser solutions. In the previous section, we discussed the role of lasers in TOPCon manufacturing (see Laser Applications In High-Efficiency Solar Cell Manufacturing)
HJT: Although conventional HJT manufacturing does not heavily rely on laser processing, recent innovations have introduced specific roles for laser technology. Laser-induced annealing is one such application that improves hydrogen passivation in HJT cells, with documented efficiency gains of up to 0.4%. This is particularly useful for reducing instability caused by light-induced degradation. However, DR Laser’s Vice President, Sales & Marketing, Ben Lee, emphasized that its adoption has been limited due to cost sensitivity, especially in China. Another promising development is the use of laser sintering for copper pastes. Unlike traditional thermal firing, this method provides localized energy delivery, enhancing paste adhesion and conductivity without heating the entire wafer. This is especially relevant for manufacturers pursuing cost-effective copper-based HJT metallization.
Laser-assisted Precision Transfer Printing (PTP) is also under exploration for HJT. This technique allows for ultra-fine finger formation, achieving line widths of under 10 μm with silver pastes and 15-20 μm with silver-coated copper pastes. These capabilities help reduce optical shading and silver usage, supporting higher efficiency and lower costs.
BC: BC solar cell architectures represent the most complex and demanding use case for laser technology. Here, laser ablation is a core process used to selectively remove multilayer rear-side stacks – often composed of BSG, PSG, polycrystalline, and nitride layers, all without damaging the underlying silicon. Because there is no thermal healing step in these architectures, the laser must operate with high precision and low energy dispersion. Lee emphasized that customer-specific customization is crucial, as manufacturers like to use vastly different rear-side layer stacks. DR Laser has developed multi-laser systems with large-area scanning and high-speed optics to accommodate these demands. Spot sizes in the range of tens to hundreds of microns are typical, depending on the process and with optics tailored to preserve layer selectivity and alignment.
Another advanced application is Laser-Induced Bonding (LIB), which is being explored for zero-busbar BC module interconnection. While not currently relevant for TOPCon or HJT, LIB could become the standard for next-generation XBC module assembly, according to Lee.
The text is an edited excerpt from TaiyangNews’ latest Market Survey on Solar Cell Production Equipment 2025, which can be downloaded for free here.