Low Cost Local Contact Opening by Using Polystyrene Spheres Spin-Coating Method for PERC Solar Cells

Area of Science:

• Materials Science
• Renewable Energy
• Semiconductor Physics

Background:

• Passivated emitter and rear cell (PERC) technology is crucial for advancing crystalline silicon solar cell efficiency.
• Traditional laser ablation for creating openings in PERCs can be energy-intensive and may impact wafer surfaces.
• Developing alternative, cost-effective, and efficient methods for PERC fabrication is essential for the solar industry.

Purpose of the Study:

• To investigate the use of spin-coated polystyrene spheres (PS) as a mask for creating local openings in PERC solar cells.
• To evaluate the effects of PS concentration and post-annealing temperature on PERC performance.
• To compare the performance of PERC devices fabricated using the PS opening technique with those made by traditional laser ablation.

Main Methods:

• Spin-coating of polystyrene spheres (PS) onto PERC wafers to create a patterned mask.
• Optimizing PS concentration and spin rate (2000 rpm) for uniform, non-aggregated sphere distribution.
• Post-annealing at 350 °C to remove PS spheres, forming holes in passivation layers without damaging the silicon wafer.
• Fabricating PERC devices using the PS opening technique and comparing their electrical performance against laser-ablated devices.

Main Results:

• Polystyrene spheres (PS) were successfully used to create openings in PERC passivation layers.
• Optimal spin-coating conditions (2000 rpm) resulted in random PS distribution without aggregation.
• PS spheres were effectively removed at 350 °C, leaving clean openings.
• PERC devices fabricated with the PS opening technique showed higher minority effective lifetime and implied open-circuit voltage compared to laser-ablated devices.
• Short-circuit current was slightly higher, while fill factor was lower due to non-optimized opening distribution.

Conclusions:

• Spin-coated polystyrene spheres offer a viable alternative to laser ablation for creating openings in PERC solar cells.
• The PS opening technique demonstrates potential for improving key solar cell performance parameters like minority carrier lifetime and open-circuit voltage.
• While conversion efficiency is comparable, further optimization of PS distribution is needed to enhance the fill factor and overall device performance.