Perylene Diimide-Based Nonfullerene Polymer Solar Cells with over 11% Efficiency Fabricated by Smart Molecular Design and Supramolecular Morphology Optimization

A series of perylene diimide (PDI) derivatives, TPP-PDI, TPO-PDI, and TPS-PDI, are developed for nonfullerene polymer solar cells (NF-PSCs) by flaking three PDI skeletons around 3D central cores with different configurations and electronic states, such as triphenylphosphine (TPP), triphenylphosphine monoxide (TPO), and triphenylphosphine sulfide (TPS). These small-molecule acceptors have a three-wing propeller structure due to their similar backbones. By changing the electron density of phosphorus atoms through oxidation and sulfuration, the folding-back strength is decreased, resulting in a less twisted molecular conformation. The stronger electron-withdrawing ability of the oxygen atom affords TPO-PDI the least twisted conformation, which enhances the crystallinity of this complex. NF-PSCs based on PTTEA:TPO-PDI exhibit a high power conversion efficiency (PCE) of 8.65%. Ultimately, the joint molecular lock effect arising from O-H center dot center dot center dot F and O-H center dot center dot center dot O=P supramolecular interactions is achieved by introducing 4,4'-biphenol as an additive, which successfully promotes fibril-like phase separation and blend morphology optimization to generate the highest PCE of 11.01%, which is currently the highest value recorded for NF-PSCs based on PDI acceptors.