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

Abstract

AbstractA 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⋅⋅⋅F and OH⋅⋅⋅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.