Thieno[3,4-c]pyrrole-4,6-dione-Based Conjugated Polymers for Nonfullerene Organic Solar Cells

Donor-acceptor (D-A) conjugated polymers have gotten significant attention in the past decades. Wide application area, ease of production, and cost-effectiveness have made the D-A conjugated polymers a pivotal class of organic electronics. Organic solar cells (OSCs) became one of the most critical application areas of conjugated polymers among many. Up to the last decade, intensive research has been conducted on fullerene-based OSCs. Drawbacks of fullerene derivatives like high cost, production obstacles, and difficulties in modifying molecular structure made the academia seek new alternatives. Emerging nonfullerene acceptors (NFAs) draw a new path for academia to tune OSCs' power conversion efficiency (PCE). With the ease of synthesis and purification, modification of molecular structure via various functional groups, NFAs start outperforming fullerene-based acceptors. Thieno[3,4-c]pyrrole-4,6-dione (TPD) is widely used in D-A conjugated polymers for high-performance OSCs. As a strong electron-withdrawing group, TPD provides deepened lowest unoccupied molecular orbital energy level and wide bandgaps when introduced into polymer backbones, enhancing optoelectronic properties photovoltaic performance. Herein, an overview of the applications ofTPD-based donor and acceptor type conjugated polymers for nonfullerene and all-polymer solar cells in the last 5 years is provided.