Key points for achieving highly foldable solar cells Compared to the normal bendable solar cells which can endure flexion with a smooth curve with radius of several millimeters, foldable solar cells can tolerate the crease at the edge with a curvature radius of sub-millimeter.
The key requirements to construct highly foldable solar cells, including structure design based on tuning the neutral axis plane, and adopting flexible alternatives including substrates, transparent electrodes and absorbers, are intensively discussed.
In the end, some perspectives for the future development of foldable solar cells, especially the standard folding procedure, improvement in the folding endurance through revealing failure mechanism, are provided.
When the solar modules subjected to folding, the Jsc started to decrease and gradually saturated at around 4 mA cm -2 after 10 cycles of folding/unfolding, while the Voc almost remained constant throughout 40 times folding/unfolding, as shown in Figure 3D. Foldable solar cells with crease in the predesigned place.
By now, carbon nanotube, graphene, ultrathin metal, metal nanowire, metal grids, conductive polymer, and their complex, have been widely applied in the robust bendable and foldable solar cells.
Zhen et al. prepared foldable polymer solar cells on woven fabric using a free-standing and wet transfer method. The fabric-based solar cells exhibited PCE of 2.90%. Moreover, they maintained 50% of initial value after folding in half for 10 cycles, supposed to be due to the low Young's modulus of woven fabrics, as shown in Figure 4C.