Investigation of high piezoelectricity in diverse metal-organic framework chemistries using high-throughput predictive modelling

Metal-organic frameworks (MOFs) are a unique class of crystalline materials with diverse applications due to their tunable porous structures and supramolecular packing. In recent years, there has been a growing interest in harnessing the piezoelectric characteristics of MOFs for sustainable technological applications, enabling their use in lead-free biomedical applications and smart devices. Advances in automated high-performance computing have facilitated the use of quantum mechanical calculations to predict the electromechanical properties of crystalline molecular materials. Through efficiently assessing the electronic and structural properties of non-centrosymmetric MOF crystal structures using high-throughput Density Functional Theory (DFT), we have conducted a comprehensive, computational analysis of single-crystal MOFs and predicted their experimentally benchmarked electromechanical properties. Notably, many of these frameworks exhibit exceptional polarisation values, with highly effective longitudinal piezoelectric coefficients (d_33^eff) coupled with intrinsically low dielectric constants. d_33^eff values of 42.1 pC/N and 28.8 pC/N represent the top-performing candidates within the set of stable, high-response MOFs. We present a detailed assessment of the elasticity and stability of these MOF crystals, as well as the structure-property relationships that give rise to technologically significant piezoelectricity. These findings open a new path for exploring the piezoelectric and mechanical properties of MOFs, which hold significant promise for applications in microelectromechanical systems (MEMS). This work highlights a broad range of electromechanical properties amongst this primary MOF crystal dataset, revealing the presence of naturally occurring longitudinal and shear piezoelectric responses that rival conventional piezoelectric materials.