Foldable Organic Photodetector with Kirigami Structure

Organic photodetectors (OPD) are promising for applications in large-area flexible electronics due to their light weight and softness of the materials. Thanks to their flexibility, the large-area flexible devices can be easily rolled up and carried, but as the size of the device increases, they become bulky. This study proposes a method for compactly folding a large-area OPD using Miura-ori strucuture, one of the origami structure which can compactly fold large-area two-dimensional planes. The Miura-ori pattern was fabricated with a 125μm polyethylene naphthalate (PEN) substrate using a kirigami-based self-folding method. Slits were cut into the substrate with a UV laser, and a heat-shrinkable film was attached. Upon heating to 140°C, this structure achieves a maximum folding angle of 104.6°. Wiring across the folds showed durability, with less than 13% resistance change after 100 cycles of folding. Furthermore, a 2×2 foldable OPD array was fabricated. To avoid crosstalk, we utilized the stacking structure organic photodiode which contains the rectifier diode and photodiode in each pixel which demonstrates selective pixel addressing. The ON/OFF ratio of the fabricated OPD was 96.7. This result suggests a design method for portable, large-area organic electronics.