Textile-fiber-embedded multiluminescent devices: A new approach to soft display systems

In the recent remarkable advances in soft electronic systems, light-emitting functions play a prominent role. In particular, polymer composite systems with embedded luminescent particles have attracted considerable attention as a luminescent component owing to their flexibility and simple fabrication. However, most flexible composite-based electroluminescent (EL) devices have coplanar structures, requiring mechanically compliant electrodes with high transmittance, durability, and stable electrical conductivity. This is a limitation for systems designed for providing superior flexible characteristics without loss of luminescence. Here, we introduce a novel EL device architecture-a durable/flexible textile-fiber-embedded polydimethylsiloxane and zinc sulfide (PDMS + ZnS) composite, driven by an in-plane electric field, which eliminates the requirement for high transmittance. On applying an AC voltage, light is radially emitted from the ZnS particles surrounding the fibers, originating from the radially distributed electric/optical fields; the rolling and stretching flexibilities are maintained during this process. The device also exhibits strong EL intensities in a thick emitting layer-a parameter on which EL and mechanoluminescent (ML) intensities in coplanar structures are dependent. This is because the electric field is applied between in-plane fibers. Using this smart design, simultaneously high EL and ML intensities can be simply achieved by embedding fibers in strong ML-emitting PDMS + ZnS. We also present a patterned device controlled by different fiber embedding depths, utilizing the vertical and in-plane electric fields. This application may provide a basis for the development of emerging soft display systems that require high luminescence as well as flexibility in the light-emitting components.