Ultraflexible and Stretchable Monocrystalline Silicon Solar Cells for Wide Ranging Deployment

Flexible and stretchable solar cells are of importance for state-of-the-art applications such as solar powered vehicles, wearables, buildings and robots, among others. While organic materials show good flexibility and stretchability, however, they generally show low efficiencies and stabilities. In terms of inorganic materials, silicon has been the material of choice in the photovoltaic industry due to its low cost, availability, low toxicity and maturity of the manufacturing process. Nevertheless, silicon is rigid and when thinned down to achieve flexibility, the material becomes brittle and the mechanical resilience of the cell is degraded. Moreover, the efficiency of the cells gets degraded too as the active material that absorbs light is thinned down. In this talk, I will discuss a corrugation technique that allows the transformation of rigid silicon solar cells into their ultra-flexible and stretchable version without thinning down the original thickness of the silicon and without degrading the normalized efficiency of the cells. The corrugation technique is based on creating alternating grooves with different shapes, resulting in interconnected islands of silicon using interdigitated back contacts. The different corrugation patterns enable different flexing and stretching capabilities, specific weight and output power which allows customization based on the application requirements. The technique allowed for the world-record flexible and stretchable inorganic solar cells which can be bent down to 140 µm radius and stretched up to twice their original size without degradation in the original normalized efficiency.