Stretchable and ultraflexible organic electronics. Stretchable and ultraflexible electronic devices have a broad range of potential uses, from robust devices for energy storage and conversion to biomedical devices that make conformal interfaces with the skin and internal organs. The articles in this issue comprehensively examine highly deformable organic electronic materials and devices. The cover image depicts a large-scale coarse-grained molecular dynamics simulation of a ~80 nm thin film of highly entangled poly(3-hexylthiophene) under uniaxial tensile deformation. Two individual polymer chains are highlighted in red. Image credit: Samuel E. Root. The inset is a schematic diagram of an organic thin-film transistor in which every component is stretchable. See the technical theme that begins on page 93.