Plastic Deformation in a Molecular Crystal Enables a Piezoresistive Response

Organic materials are promising candidates for the development of efficient sensors for many medicinal and materials science applications. Single crystals of a small molecule, 4‐trifluoromethyl phenyl isothiocyanate (4CFNCS), exhibit plastic deformation when bent, twisted, or coiled. Synchrotron micro‐focus X‐ray diffraction mapping of the bent region of the crystal confirms the mechanism of deformation. The crystals are incorporated into a flexible piezoresistive sensor using a composite constituting PEDOT: PSS/4CFNCS, which shows an impressive performance at high‐pressure ranges (sensitivity 0.08 kPa−1 above 44 kPa). Single crystals of 4‐trifluoromethyl phenyl isothiocyanate exhibit plastic deformation in the form of bending, twisting and coiling. The compliant behaviour of this compound provides an improved piezoresistive response in a composite pressure sensing device.