Fully 2D and 3D printed anisotropic mechanoluminescent objects and their application for energy harvesting in the dark

We report on new material compositions enabling fully printed mechanoluminescent 3D devices by using a one-step direct write 3D printing technology. The ink is composed of PDMS, transition metal ion-doped ZnS particles, and a platinum curing retarder that enables a long open time for the printing process. 3D printed mechanoluminescent multi-material objects with complex structures were fabricated, in which light emission results from stretching or wind blowing. The multi-material printing yielded anisotropic light emission upon compression from different directions, enabling its use as a directional strain and pressure sensor. The mechanoluminescent light emission peak was tailored to match that of a perovskite material, and therefore, enabled the direct conversion of wind power in the dark into electricity, by linking the printed device to perovskite-based solar cells.