Control of Spontaneous Orientation Polarization in Organic Semiconductors: The Role of Molecular Structure and Film Growth Condition

Spontaneous orientation polarization (SOP) occurs when molecules with a finite permanent dipole moment are grown as thin films by physical vapor deposition and their alignment is such that a net non-zero polarization remains. We discuss how SOP in organic semiconductors can be controlled by the design of molecules as well as the film growth conditions and discuss its relevance in organic light-emitting devices.