Impact of Organic Particles from Wafer Handling Equipment on Silicon Heterojunction Pseudo-Efficiency

Within this paper a systematic analysis of particle transfer onto SHJ Solar cell precursors by handling with suction cups and the impact on the pseudo efficiency is presented. The study establishes a correlation between particle area coverage and a resulting loss of pseudo solar cell parameters. The analysis was carried out on one hand by means of SEM measurements at the contact points between suction cup and wafer to quantify particle transfer and on the other hand by means of suns photoluminescence imaging measurements to evaluate the resulting losses. It is shown that the choice of contact material and the wafer temperature have a significant influence on the transferred particle number, their size and the resulting particle area coverage. A local electrical defect was observed at these particle-rich spots, which also affected a larger area around this insufficiently passivated region. This had a significant negative effect on the pseudo efficiency, which is more pronounced for increasing particle area coverage. If the particle density is increased by 0.1 % within an area of 800 mm2, the pseudo efficiency in this area decreases by almost 1.2 %Relative. The correlation found can be used to predict an efficiency loss using standard photoluminescence images.