Cover Image, Volume 49, Issue 10


original image

Alignment layers can be used to fabricate ordered polymer films for applications in electronics such as polarized organic light-emitting diodes, anisotropic field-effect transistors, and polarization-sensitive photodiodes. Traditionally, rubbed polyimide films have been used to create such alignment, but this method requires high-temperature baking and rubbing in addition to thermal annealing, causing mechanical damage, dust generation and incompatibility with plastic substrates. On page 725 of this issue, Shaw Chen and colleagues introduce a room-temperature processing technique. A coumarin-based polymer was irradiated to create the alignment layer, on which a conjugated oligomer film was solution cast for solvent-vapor annealing to create a monodomain oriented active layer. The researchers achieved orientational order parameter values identical to those on traditional rubbed polyimide layers using the new, low-temperature technique.