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

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.