Emergent functionalities enhanced by mechanical stress in SnO2-based flexible devices

Emergent functionalities created by applying mechanical stress to flexible devices using SnO₂ microrods and Ga₂O₃/SnO₂-core/shell microribbons are reviewed. Dynamic lattice defect engineering through application of mechanical stress and a voltage to the SnO₂ microrod device leads to a reversible semiconductor-insulator transition through lattice defect creation and healing, providing an effective and simple solution to the persistent photoconductivity (PPC) problem that has long plagued UV semiconductor photosensors. Here, lattice defects are created near slip planes in a rutile-structured microrod by applying mechanical stress and are healed by Joule heating by applying a voltage to the microrod. Nanoscale amorphous structuring makes the Ga₂O₃/SnO₂-core/shell microribbon with a large SnO₂ surface area more sensitive to changes in temperature, while mechanical bending of the wet device improves its sensitivity to adsorbed water molecules. These results illustrate the potential for developing flexible devices with new functionalities by enhancing the intrinsic properties of materials through miniaturization, mechanical stress, and hybridization.