2D Layered Dipeptide Crystals for Piezoelectric Applications

Abstract

2D piezoelectric materials such as transition metal dichalcogenides are attracting significant attention because they offer various benefits over bulk piezoelectrics. In this work, the fabrication of layered biomolecular crystals of diphenylalanine (FF) obtained via a co‐assembly of l,l‐ and d,d‐ enantiomers of FF monomers is reported. Their crystal structure, thermal and chemical stabilities, and piezoelectric properties are investigated. Single crystal X‐ray diffraction results show that FF enantiomers are arranged in the form of bilayers consisting of monomers with alternating chirality packed into a tape‐like monoclinic structure belonging to a polar space group P21. Each bilayer (≈1.5 nm thick) demonstrates strong out‐of‐plane piezoelectricity (d33 ≈ 20 pm V−1) that is almost an order of magnitude higher than in the archetypical piezoelectric material quartz. The grown crystals demonstrate better thermal and chemical stabilities than self‐assembled hexagonal FF nanotubes studied in the past. Piezoelectric bilayers, being held via weak aromatic interaction in the bulk crystals, can be exfoliated by mechanical or chemical methods, thus resulting in a 2D piezoelectric material, which can find various applications in biocompatible and ecologically friendly electromechanical microdevices, such as sensors, actuators, and energy harvesting elements used in implantable and wearable electronics.

Piezo-Responsive Hydrogen-Bonded Frameworks Based on Vanillin-Barbiturate Conjugates

“…Low-frequency piezoresponse force microscopy (PFM) study in contact mode (corresponding force–distance curves are given in Figure S7 ) of the powders of compounds 3a and 3b transferred to aluminum foil revealed that the average amplitude of the piezo signal from photodetector was much higher in the case of compound 3a as compared with compound 3b ( Figure 3 ) (full experimental details are given in Materials and Methods section and references therein [ 19 , 20 ]). Conversion of the vertical PFM signal values into the d 33 coefficient provided the average values of 2.74 ± 0.54 (compound 3a ) and 0.57 ± 0.11 pm/V (compound 3b ).…”

Electronic pyroelectricity: the interplay of valence tautomerism and spin transition

“…If no dielectric anomaly is observed in this regime, the compound can be considered piezoelectric or pyroelectric rather than ferroelectric. 20,21 Among the array of valence tautomeric compounds reported so far, the pyroelectric properties reported by Sato and coworkers can be observed in the absence of an electric field because the molecular orientation in the molecular crystals is fixed. 18,19 Moreover, the advanced design strategy can improve the predictability and precision during the incorporation of polar molecular crystals into energy-efficient materials.…”

“…If no dielectric anomaly is observed in this regime, the compound can be considered piezoelectric or pyroelectric rather than ferroelectric. 20,21…”

Enhanced Piezoelectric Properties Enabled by Engineered Low-Dimensional Nanomaterials

“…Among the LD piezoelectric materials, many of them show piezoelectric effects in both bulk and their LD counterparts. − These materials included both layered and nonlayered structures. The bulk form with the piezoelectric feature has been widely adopted in sensors, actuators, and many other microsystems.…”