3D Integrated Photovoltaic Surfaces for Portable Applications

To enable the use of portable, and potentially wearable, 3D molded autonomous energy modules the applicability of high pressure injection overmolded flexible solar cells was investigated [1]. The goal was to find commercially available flexible amorphous Si photovoltaic (PV) modules, test their overmolding possibilities and to investigate overmolding materials of the PV as a baseline for future studies. The devices’ electrical behavior was measured under different conditions and in an outdoor test environment. Based on processing and testing, the goal was to evaluate the manufacturing possibilities of a 3D integrable autonomous energy module for wearable plastic/composite equipment. The investigation was divided into three sub-tasks: 1) material design, 2) PV device overmolding, and 3) testing. Regarding materials, commercial solar cells made of amorphous silicon were used in the project due to their easy availability, and two materials were tested for overmolding: polycarbonate (PC) and thermoplastic polyurethane (TPU). For the overmolding process, various parameters were evaluated, with the TPU being a more suitable material for the selected PV devices. Finally, the overmolded cells were tested under different lighting conditions, bending stress, accelerated ageing, and the effect of scratching and dirt on the cell's operation was studied.