Harvesting of shear piezoelectricity in a molded multicomponent crystal disc

•Successful crystallisation of the multicomponent solid, S-Mand•L-Lys•5H2O, made from two components which have diverse and challenging crystallisation behaviours.•Demonstrates a single crystal d33 of 3.5pC/N, but a polycrystalline d33 of 11 pC/N at the macroscale due to contributions from shear piezoelectric components induced in the triclinic structure.•The brittleness of the crystals (E = 37 GPa) is overcome by reinforcing the substratefree piezoelectric disc with a thin polymer coating to prevent flaking.•DFT-calculated crystal, intramolecular, and intermolecular dipoles substantiate the nanoscale origins of the anisotropic piezoelectric responses. Biomolecular piezoelectrics, such as amino acids and peptides, exhibit significant shear piezoelectric responses in single crystal form. However, naturally occurring longitudinal piezoelectricity is rare and, when present, is dampened due to the multi-directional self-assembly in polycrystalline device layers. Here we utilise cocrystallisation to engineer a multicomponent crystalline salt hydrate of S(+)Mandelic Acid and LLysine, S-Mand•L-Lys•5H2O (1). This material exhibits a predicted single crystal longitudinal piezoelectric response of d33 = 3.5 pC/N. In polycrystalline form, 1 grows as an assembly of plates which increases the measured longitudinal piezoelectricity to 11 pC/N in its macroscopic solid-state. This is due to contributions from the shear piezoelectric response d36 = 10.8 pC/N, originating from the presence of plates oriented at acute angles relative to the surface. The brittleness of the crystals (E = 37 GPa) is overcome by reinforcing the substrate-free piezoelectric disc with a thin polymer coating to prevent flaking. Structural analysis confirms that the triclinic structure of 1 gives rise to this increased response due to the relative orientations of individual crystallites. Confined crystallisation of this multi-component form with a plate-like morphology, results in macroscopic self-assembly of an amino acid cocrystal that allows for the harvesting of higher shear piezoelectricity, but in a facile longitudinal configuration. [Display omitted]