Non‐Corrosive Conjugated Polyelectrolyte as Anode Interlayer for Efficient and Stable Organic Solar Cells: Over 20% Photovoltaic Efficiency and 82.2% Fill Factor

ABSTRACT Although power conversion efficiencies (PCEs) of organic solar cells (OSCs) have exceeded 20%, their fabrications have to rely on acid‐doped anode interlayers (AILs), which brings serious corrosion problems. Undoubtedly, non‐corrosive AILs are indispensable for the industrialization of OSCs, but they hardly exhibit comparable performances to acid AILs, such as the classic PEDOT:PSS. Herein, we designed and synthesized two pH‐neutral conjugated polyelectrolytes (CPEs) with straight linear conformation as AILs for efficient and stable OSCs. Compared to the zigzag CPE, the linear IDT‐F exhibits a dominant face‐on orientation, which can form an intermolecular packing pathway that well coincides with the charge transport direction in OSCs. Consequently, the IDT‐F‐based AIL exhibits an exceptional hole‐transporting capability, even suppressing that of PEDOT:PSS. By utilizing the IDT‐F‐based AIL, an unprecedented PCE of 20.06% was achieved in the binary OSC, along with a fill factor of 82.2%. This not only represents the best performance reported to date for OSCs using a non‐corrosive AIL but also substantiates that a CPE‐based AIL can provide photovoltaic efficiencies exceeding 20%. Importantly, the IDT‐F‐based AIL can address the corrosion issues in OSCs due to the excellent chemical inertness, boosting a high device stability, so as to pave the way for practicable OSCs.