Atomic-resolved hierarchical structure of elastic π-conjugated molecular crystal for flexible organic photonics

Abstract

<h2>Summary</h2> Achieving multifunctional elastic conjugated molecular crystals is a huge challenge for flexible optoelectronic application due to the difficulty in precise control of non-covalent interactions that cause an inherent rigidity and brittleness impression of crystals. Here, we demonstrated the atomic-resolved structural perturbations of a <i>racemic</i> fluorenol-carbazole (PhOH-Cz) elastic π-conjugated molecular crystal for flexible naked-eye-visible and color-tunable afterglow waveguide. Its outstanding elastic property is derived from the synergistic effect of interlayer hierarchical slippage and the intralayer molecule perturbations, which provide a physical platform to absorb and release the mechanical energy and avoid brittle fracture. The atomic-resolved structural perturbations in the bent elastic crystal visually confirmed the molecular movements leading to breaking and re-forming of hydrogen-bonding interactions. These exceptional observations will be useful to systematically investigate photophysical behavior of conjugated materials. Finally, the flexible naked-eye-visible and color-tunable afterglow waveguides that were fabricated confirmed the potential application of elastic crystal in flexible organic photonics.