Regulating the Sequence Structure of Conjugated Block Copolymers Enables Large‐Area Single‐Component Organic Solar Cells with High Efficiency and Stability

Abstract

Single‐component organic solar cells (SCOSCs) based on conjugated block copolymers (CBCs) by covalently bonding polymer donor and polymer acceptor become more and more appealing, due to the formation of favorable and stable morphology. Unfortunately, deeply understanding the effect of the assembly behavior caused by sequence structure of CBCs on the device performance is still ambiguous. Herein, from the aspect of manipulating the sequence length and distribution regularity of CBCs, we synthesized a series of new CBCs, namely D18(20)‐b‐PYIT, D18(40)‐b‐PYIT and D18(60)‐b‐PYIT by two‐pot polymerization, and D18(40)‐b‐PYIT(r) by traditional one‐pot method. It is observed that precise manipulation of sequence length and distribution regularity of the polymer blocks fine‐tunes the self‐assembly of the CBCs, optimizes film morphology, improves optoelectronic properties and reduces energy loss, leading to simultaneously improved efficiency and stability. Among these CBCs, the D18(40)‐b‐PYIT‐based device achieves a champion efficiency of 13.4% with enhanced stability, which is the outstanding performance of SCOSCs. Importantly, the regular sequence distribution and suitable sequence length of the CBCs enable a facile film‐forming process of the printed device. For the first time, the blade‐coated large‐area rigid/flexible SCOSCs are fabricated, delivering an impressive efficiency of 11.62%/10.73%, much higher than their corresponding binary devices.

Nonfullerene Acceptors with Aromatic Heterocycle Substitutions for Efficient Organic Solar Cells

“…With the increasing demand for eco-friendly and sustainable energy, solution-processed bulk-heterojunction organic solar cells (OSCs) have attracted considerable attention owing to their inherent advantages in printing fabrication, cost-effectiveness, flexibility, and lightweight properties. − In recent years, nonfullerene acceptors (NFAs), particularly small-molecule acceptors (SMAs), have demonstrated significant progress. The development and design of numerous SMAs have invigorated the field of organic photovoltaics, leading to advancements in the OSC power conversion efficiency (PCE) of up to 19%. ,− Among the various fused-ring SMAs, those adopting acceptor–donor–acceptor (A–D–A) and A-DA 1 D-A-type molecule structures, such as ITIC and Y6, are esteemed for their exceptional device performance. − Typically, these SMAs comprise three essential components: a fused-ring core, side chains, and electron-withdrawing end-groups.…”