Steady cost pressure in silicon solar cell production leads to a continuous reduction of silver consumption per cell. Pattern Transfer Printing (PTP) technology enables to reduce silver consumption by depositing smaller front electrodes on solar cells. Here, we aim at a better understanding of the laser deposition process. The aspect ratio of printed lines improved with increasing paste yield stress but was lower than the theoretical aspect ratio for a given trench geometry, suggesting that line spreading was caused by the pressure that was due to the vaporization of volatile paste components and a yield stress reduction that was due to local paste heating. A low laser power threshold, mandatory to fabricate narrow electrodes with a high aspect ratio and low amount of debris, could be achieved using pastes with low boiling temperature of volatile components and poor wetting between paste and film. The material with the lowest light transmission exhibited the lowest laser power threshold. We attribute this to the weaker adhesion to the paste and a better alignment with the laser focal plane. Our results provide valuable guidelines for paste and film material design aimed at narrower electrodes, with a higher aspect ratio to be obtained at an even lower laser power threshold in PTP-based solar cell metallization.

中文翻译：

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图案转移印刷（PTP）技术的厚膜浆料流变学和薄膜材料的研究

硅太阳能电池生产中稳定的成本压力导致每个电池的银消耗量持续减少。图案转移印刷（PTP）技术可通过在太阳能电池上沉积较小的前电极来减少白银消耗。在此，我们旨在更好地了解激光沉积过程。印刷线的纵横比随糊料屈服应力的增加而改善，但低于给定沟槽几何结构的理论纵横比，这表明线散布是由于挥发性糊剂成分汽化和屈服应力降低而引起的压力引起的。那是由于局部糊状加热。低激光功率阈值，必须制造出具有高纵横比和少量碎屑的窄电极，使用挥发性组分的沸腾温度低且糊剂与薄膜之间润湿性差的糊剂可以实现此目的。具有最低透光率的材料表现出最低的激光功率阈值。我们将其归因于对糊剂的较弱粘附力以及与激光焦平面的更好对准。我们的结果为针对较窄电极的糊料和薄膜材料设计提供了有价值的指导，在基于PTP的太阳能电池金属化中，即使在更低的激光功率阈值下也可以获得更高的纵横比。