Clean glass separation from end-of-life photovoltaic modules via photothermal softening

The primary challenge in efficient recycling of end-of-life photovoltaic (PV) modules lies in clean glass separation. This study investigated the softening behavior of ethylene-vinyl acetate copolymer (EVA) in end-of-life PV modules at moderate temperatures (70-170 °C), with the aim of enabling photothermal-induced softening for efficient glass separation. By applying controlled localized heating to waste PV modules-analogous to concentrated solar irradiation-the study systematically examined the individual and combined effects of temperature, heating duration, and irradiation angle on separation efficiency. Results show that under the optimal conditions (167.8 °C, 1126 s heating duration, and 90° irradiation angle), the theoretically predicted maximum glass separation rate reached 41.51 %, while the experimentally verified value was 41.23 %. A multiscale analysis incorporating molecular dynamics, macroscopic mechanical properties, and rheological behavior revealed that under this optimal condition, EVA underwent synergistic transformations across scales: intense activation of molecular segments, a sharp decline in storage modulus, and a sudden drop in zero-shear viscosity. These changes collectively led to a critical loss of interfacial adhesion and cohesive strength, enabling clean interfacial separation under low mechanical stress. This study provides a novel approach for the environmentally friendly recycling of end-of-life PV modules.