The stress and strain caused by folding are highly localized at the creases and suppressed on the facets. Origami 25, 26, an ancient form of papercraft, is the folding of 2D sheets into 3D structures through specifically designed patterns. Origami-based structures, as demonstrated in this paper, can outperform these previous structures. Furthermore, nearly all curved displays rely on stretchable interconnects and encounter problems including limited deformability, complex manufacturing processes, high costs, and low yields that hinder mass production. Materials for this type of stretchable display still need to work as holding substrates, which results in limitations similar to those of previous types of devices. 24 also reported a 32 × 32 active matrix light-emitting diode (AMLED) stretchable display in which the pixels are connected via 2 mm long horseshoe metal interconnects. The serpentine microribbons detached from the substrate and formed noncoplanar pop-up bridges after releasing the prestrain the array reached 48% stretchability and was compatible with spherical surfaces 23. developed a technology that used serpentine-shaped interlinks to connect pixels, and the connected μ-ILED array was then transferred to a 400 μm-thick prestretched PDMS sheet. Another strategy for stretchability is to employ geometrically stretchable interconnects to connect rigid islands of illuminant elements. Unfortunately, stretchable materials such as polydimethylsiloxane (PDMS), Eco-flex rubbers, and poly(3,4-ethylene dioxythiophene) (PEDOT) 22 often suffer from low stiffness and short fatigue life, resulting in the luminescent or conductive materials embedded in them being damaged due to large deformation. These stretchable displays can fit different nondevelopable surfaces by stretching. 12 reported a stretchable active-matrix display that integrates printed elastic conductors (fluorinated rubber), organic transistors, and OLEDs to sustain 30–50% strain and that can be wrapped on a spherical surface. The ZnS phosphors were embedded in Eco-flex 00–30 to emit light when an AC voltage was applied to the two electrodes made by an elastomeric matrix (polyacrylamide, PAM). 21 reported an AC-driven stretchable capacitive display. The application of stretchable materials in curved displays should overcome the difficulties associated with nondevelopable surfaces 1. Stretchability can be realized by mounting rigid devices on a stretchable substrate or by connecting island-type small devices with serpentine interconnects. Therefore, stretchability is essential for achieving generally curved displays. According to Gauss’s Theorema Egregium in geometry 19, 20, due to the constancy of the Gauss curvature (GC, K) of a surface under local isometry, flexible but nonstretchable displays cannot be bent into nondevelopable surfaces with nonzero GC the commercial products mentioned above can only be bent into developable surfaces such as tubes or cones. However, these types of displays are flexible but nonstretchable. A novel organic liquid crystal display uses an organic thin-film-transistor (TFT) array on a plastic film to replace amorphous silicon TFTs and has achieved a certain amount of flexibility 18. As a typical example, organic light-emitting diode (OLED) displays can be fabricated on flexible substrates to achieve flexibility 16, 17 and have already been commercialized. Flexible displays 13, 14, 15 have been developed extensively and have mainly been used in household appliances and consumer electronics. One way to realize a curved display is by bending a flexible display. As an indispensable way to access information and gestures, curved displays 11, 12 are one of the key components for curved electronics and constitute functional and attractive next-generation displays. Curved electronics 1 have recently undergone rapid development, covering broad application areas including wearable sensors, smart skins, curved optics, smart appliances, soft robotics, and even home decorations 2, 3, 4, 5, 6, 7, 8, 9, 10. Curved surfaces, which seem ubiquitous in our daily lives, are desirable for designers for aesthetic and/or practical considerations.
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