Quantitative Prediction of the Electro-Mechanical Response in Organic Crystals

Organic semiconductors’ inherent flexibility makes them appealing for advanced applications such as wearable electronics, e-skins or pressure sensors and can even be used to enhance their intrinsic electronic properties. Unfortunately, these applications for organic materials are currently hindered by the lack of a quantitative understanding of the interplay between their electrical and mechanical properties. In this work, we fill this gap by presenting an accurate methodology able to predict quantitatively the effects of external deformation on the charge transport properties of any organic semiconductors. Three prototypical materials are investigated, showing that the experimental variation of charge carrier mobility with strain is fully reproduced, even in a wide range of deformations applied along different crystal axes. Our results point out that the intrinsic electro-mechanical response of the materials varies by orders of magnitude within the class of organic semiconductors, a difference rationalized observing that the mobility trend is primarily influenced by transfer integrals’ variation, rather than by a modification of the crystal phonons. In light of its robustness, accuracy and low computational cost, this protocol represents an ideal tool to quantify the electro-mechanical response in new organic compounds, thus establishing a reliable route for a full exploitation of strain engineering in advanced technologies.