Investigations on the delamination mechanism of double-glass photovoltaic modules based on laser treating

Abstract

The growing number of decommissioned photovoltaic (PV) modules calls for efficient recycling methods with minimal material damage. This study developed a preheating-assisted pulsed laser strategy for interfacial delamination of double-glass crystalline silicon PV modules and investigated the underlying mechanisms. Preheating softened the EVA encapsulant and broadened the laser-processing window, although preheating alone was insufficient to induce EVA/Si delamination. Among the investigated conditions, a heater setpoint of 200 °C provided the widest stable-delamination window. The laser beam passed through the top glass and upper EVA encapsulant with limited optical loss and was predominantly absorbed by silicon. Four characteristic states emerged with increasing laser energy density: non-separable, difficult-to-delaminate, stable delamination, and carbonized delamination. Interfacial weakening involved coupled responses of EVA, the SiN x antireflection layer, and the silicon surface. EVA deacetylation reduced the abundance of polar ester groups and weakened chemical adhesion, while damage to the SiN x layer and localized silicon melting–resolidification altered the interfacial bonding environment and reduced mechanical interlocking. Transient pressure from localized vaporization and volatile-product release may have further assisted crack propagation across regions where the pyramidal texture remained intact. These coupled effects enabled relatively continuous EVA/Si delamination with limited material damage. Excessive energy input caused EVA carbonization, severe surface ablation, and silicon fracture. These findings provide a mechanistic basis for process optimization and low-damage recovery of materials from double-glass PV modules.