Stretchable
electronics has enabled many unforeseen applications
in a variety of fields. Mechanical design concepts to achieve the
stretchability without affecting the device functionality, however,
are limited to few known practices, such as mechanical buckling, serpentine
shape, or simple elastomeric composites. In this paper, we propose
another mechanics design principle for high stretchability (>100%)
based on the composite of vertical array of Si micropillars embedded
into elastomer poly(dimethylsiloxane). The orthogonalization of active
functional elements to applied strain direction enables highly stretchable
electronic devices, where the applied strain is mostly absorbed into
elastomer on interpillar space. On the other hand, the vertical pillars
do not experience any noticeable strain at all. As a proof-of-concept
demonstration, we fabricate stretchable Si-organic hybrid solar cells
using such a design and the cell shows reasonable level of cell efficiency
compared with planar counterparts. The cell can be stretched reversibly
without any noticeable performance degradation. Furthermore, the cell
can be operated in a bifacial mode by employing stretchable, transparent
Ag nanowire-based electrodes. The mechanical design for stretchability
demonstrated here would provide new opportunities for stretchable
electronics.