Review on Indacenodithiophene (IDT) and Perylene Diimides (PDIs) Based Non-Fullerene Acceptors in Organic Solar Cells: Progress and Challenges

Abstract The non-fullerene acceptors (NFAs) are dominating thin-film organic solar cells (TFOSCs) research, in recent years, because of their record high power conversion efficiency (PCE). Currently, the PCE of NFAs-based solar cells reaches 19.36%, which is much higher than the fullerene-based counterparts. The NFAs offer several advantages over the fullerene, and consequently, attracted a growing interest in the field of TFOSCs. The vast majority of the research reports are based on electron deficient acceptor–donor-acceptor (A-D-A) type small molecules that follow a simple synthesis route. A-D-A offers low photons energy losses resulting in high open-circuit voltage $$({V}_{oc})$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mo>(</mml:mo> <mml:msub> <mml:mi>V</mml:mi> <mml:mrow> <mml:mi>oc</mml:mi> </mml:mrow> </mml:msub> <mml:mo>)</mml:mo> </mml:mrow> </mml:math> and tunable energy bandgaps for efficient collection of the charges. The effect of energy loss on the performance of non-fullerene based TFOSCs was deliberated in terms of changes in energy offset and morphology of the acceptor and donor molecules blend films. Controlling the energy loss and film morphology through material synthesis and new device structure can lead to more successful performance in TFOSCs. This review focuses on the recent research progress based on indacenodithiophene (IDT) and perylene diimides (PDIs) core donor moieties for the purpose of solar energy harvesting via solution-processed TFOSCs. The influence of the new molecule acceptors’ chemical and structural properties was deliberated based on tuning energy levels, film morphology, and charge mobility. Finally, the challenges of NFAs are also presented in summary and perspective.