Advancements on Post-Processing of High Efficiency Cells: Data from Mass Production and Experimental Roadmap

The power output and conversion efficiency of solar cells can change after exposure to illumination, with increases or decreases depending on the cell structure. According to the literature, high-intensity light exposure combined with controlled heating can enhance the performance of amorphous-crystalline silicon heterojunction (HJT) solar cells and modules [1]. This efficiency improvement is attributed to simultaneous defect recovery and reductions in series resistance. In this work, we present a rapid post-treatment process for HJT solar cells, utilizing an LED-based oven jointly designed by Applied Materials (AMAT, Italy) and CEA-INES (France), in collaboration with 3Sun (Enel Group, Italy). The architecture of the developed Fast Light Soaking (LS) solution is described in detail in [2]. Using the Fast Light Soaking process at lab scale, we achieved an efficiency gain of up to +0.6%, with open-circuit voltage (Voc) and fill factor (FF) generally being the main contributors to this improvement [2]. In this paper, we provide an overview of the latest achievements obtained with the Fast Light Soaking process, including: i) data collected in mass production, ii) the effect of the Light Soaking process on cells from different efficiency classes, and iii) a detailed degradation analysis after LS. The impact of Light Soaking on different metallization processes, using various silver- and copper-based pastes, will also be reported. Preliminary results on the effect of the Light Soaking process on HJT cells with an nc-Si:H n-doped silicon layer, as well as on TOPCon cells, will be presented as part of our experimental roadmap.