Evidence of the improvement of photovoltaic efficiency by polar molecule orientation in a new semiconducting polymer

Storage of an internal field in a polymeric semiconductor device should be of great interest for applications like photovoltaic solar cells to facilitate exciton dissociation and improve charge transport in the structure. Orientation of polar molecules, contained inside a polymer binder, induces a rectifying effect, behaving as a distributed homojunction within a single polymeric film. To investigate this concept, a new poly(p-phenylenevinylene) (PPV) derivative bearing push–pull like molecules was purposefully designed and synthesized. Effect of polar molecules’ orientation on carrier injection and transport properties was studied. In the test systems, we demonstrate an increase of the external quantum efficiency upon orientation.