"π-figuration" for controlling stacking of π-conjugated molecules and polymers

π-Conjugated molecules and polymers are expected to have a variety of applications in organic electronics. Control over how these π-conjugated systems stack in the solid state is crucial for utilization of their desirable photophysical and electrical properties. Some molecules need to be designed with enhanced π-stacking abilities, whereas others might display novel properties as a result of restricting their π--stacking abilities. Furthermore, π-conjugated molecules or polymers that display partial π-stacking are of interest for potential new applications because of the synergy of the contrasting properties of stacked and isolated π-conjugated systems. Here, we highlight recent progress in molecular design to control π-stacking, with a particularly focus on the redox properties of these unique molecular systems.