Si solar microcells for modules with reduced purity requirements, high voltage outputs and mechanically stretchable designs

We recently reported a strategy, in which modules consist of large-scale arrays of small, interconnected ultrathin (i.e. 1-20 ¿m) Si microcells (¿-cells) formed by anisotropic etching of bulk wafers and integrated with a soft printing technique. Here we report three new advances in this type of printed, ¿-cell technology. First, we show that ¿-cells formed with low purity, solar grade wafers (Dow Corning^® 101 SOG Si metal), can achieve efficiencies much higher than those possible with corresponding bulk cells formed with the same material. Second, we demonstrate high voltage mini-modules that incorporate these ¿-cells and lead to high voltage outputs. Finally, we demonstrate the fabrication of mechanically stretchable solar cell modules which are non-coplanar (i.e. arch shaped). The results show that these materials and designs yield a stretchable layout that can undergo strains of up to 30% without failure.