Novel Wide Bandgap Polymer Donors Containing Benzodithiophene and Substituted-Thiophene as Donating and Accepting Units for High Performance Non-Fullerene Acceptor Based Organic Solar Cells

Abstract

Organic solar cells (OSCs), or organic photovoltaics (OPVs), have attracted widespread attention as a promising technology for converting solar energy to electricity owing to their advantages of good mechanical flexibility, lightweight, low-cost and large-area fabrication durability. Over the decades, OSCs have improved rapidly since Heeger’s group reported the first bulk heterojunction (BHJ) OSC which is composed of a blend active layer containing a p-type conjugated polymer as a donor and an n-type small molecule organic semiconductor as an acceptor. Recently, significant progress has been achieved with the highest power conversion efficiency (PCE) over 19%, ascribed to the rational design and matching of the conjugated polymer donors with the novel non-fullerene acceptors (NFAs). By reviewing the remarkable progress achieved for OSCs in the past three decades, it is noteworthy that the benzodithiophene (BDT) and thiophene units showed much potential for constructing polymer donors which showed great photovoltaic performance. However, several challenges remained with further development of OSCs including cost-efficiency. It is important to develop new wide bandgap (WBG) conjugated polymer donor materials to balance material cost and device efficiency for high performance NFA-based solar cell towards commercialization.