Charge transport and transfer phenomena involving conjugated acenes and heteroacenes

Conjugated acenes are very promising for their applicability in different optoelectronic devices. In particular, pentacene (PCn) shows some distinct behaviours, namely high optical absorption and remarkably high carrier mobility which makes it as a landmark semiconductor for use in field-effect transistors or hole transporting materials in organic photovoltaics. During the last few decades, a large number of theoretical and experimental researches has been performed showing the practical applicability of different acenes and heteroatom-doped acenes (heteroacenes). Few reviews are also made in this regard. However, correlating the molecular properties arising from their intrinsic electronic structures with their charge transfer (CT) and transport characteristics is really scattered. Furthermore, very recent understandings on the nanojunctions made of acenes along with suitable electrodes need to be reviewed for further development of their performances in electronic devices. At the same time, the photovoltaic applicability of acenes and heteroacenes has recently been shown as an interplay of the dynamics of CT states as well as the intrinsic charge separation within the molecules or composites. The present review aims to point out those recent observations so as to draw more attention for further development in the area of acene- and heteroacene-based optoelectronic devices. We concentrate more on the structure–property relationships which could guide the device performance. As the subject area is so vast, we put emphasis on the very recent studies on PCn and some lower S,N-heteroacenes.