Present and Future Perspectives of Low Band Gap Polymers Towards Organic Photovoltaics

Since the discovery of conjugated polymers is utilized for many applications in various field, at present conjugated polymers have received increasing attention due to their intriguing electronic and optoelectronic properties for application in a variety of optoelectronic devices, such as polymeric light-emitting diodes (PLEDs), organic thin film transistors (OTFTs), and organic photovoltaics (OPVs). Such applications encourage the continued exploration of conjugated polymers with new structures. Donor-Acceptor (D-A) architecture copolymers are of much interest because of the facile tailoring of electronic structure. The independent selection of electron donating and accepting moieties facilitates the tuning of the HOMO and LUMO energy level, energy band gap, photon absorption, and charge carrier transport (p-type, n-type, or ambipolar). The present article is mainly review on the various D-A frame work of polymers for OPVs application. Herein we want to describe the various donor and acceptors units for such polymers, along with the strategies of bandgap tuning with the HOMO and LUMO. The effect of electron rich groups on donor and electron withdrawing groups on acceptor are discussed in detail.