Unusual electromechanical effects in organic semiconductor Schottky contacts: Between piezoelectricity and electrostriction

The converse electromechanical response in an organic Schottky contact follows a power law dependence S∝Vα of the mechanical strain S versus the applied voltage V, with an exponent α=1.5, in between linear piezoelectricity and quadratic electrostriction. The experimental result is discussed within the frame of a model, where the Coulomb attraction between charged impurities present in the depletion zone of the Schottky contact and the charges accumulated in the metal at the interface with the semiconductor is considered. Electromechanical responses of such devices appear to be of fundamental interest for the investigation of nonuniform electric field distributions and for potential practical applications as electromechanical transducers.