Suppressing VoltageLoss and Improving Charge Generationvia Fluorinated Molecular Backbone of Low-Cost Polymers for EfficientOrganic Solar Cells

High efficiency and low cost are indispensable for the industrialization of organic solar cells (OSCs), which urgently needs to be addressed. Herein, three simple-structure terpolymer donors, PTQ13-5, PTQ13-10, and PTQ13-15, are developed by embedding a simple fluorinated unit 3-fluorothiophene (T-F) into the molecular backbone of polymer PTQ10 to pursue low-cost and high-efficiency organic photovoltaic molecules. Three terpolymers show obviously low-cost characteristics due to their short synthesis routes and high total synthetic yields from cheap raw materials. The introduction of the T-F unit leads to the blue-shifted absorption, down-shifted HOMO levels, and more favored molecular aggregation morphology of terpolymers, mainly due to the strong electron-withdrawing property of the F atom, along with the presence of noncovalent F···H interactions. As a result, the PTQ13-5-based OSC achieves enhanced power conversion efficiency (PCE) of 18.42% due to suppressed voltage loss (<i>V</i>_loss) because of low nonradiative loss of 0.189 eV and enhanced charge generation; this is one of the highest PCEs for OSCs based on low-cost organic photovoltaic materials. This work suggests that fluorination of the polymer backbone is an effective strategy to suppress <i>V</i>_loss and improve charge generation of OSCs, and it offers a rational guide in the design of organic photovoltaic molecules with low cost and high performance.