Over 20% Efficiency Organic Solar Cells via Intramolecular Charge Transfer in a Self‐Doped Polymerized Conductive PEDOT Interlayer

ABSTRACT Widely utilized as an HTL in OSCs owing to its conductivity and solution processability, PEDOT: PSS suffers from an insulating PSS shell that restricts conductivity and induces colloidal instability. Although additive‐based methods can partially alleviate these drawbacks, they bring about adverse effects, incomplete PSS elimination, and complex synthesis. Here, we report s ‐PEDOT: POM, a novel self‐doped PEDOT derivative synthesized through POM‐mediated oxidative polymerization. This approach effectively removes PSS while retaining sulfonate groups, ensuring solubility and self‐doping capabilities. The resulting s ‐PEDOT:POM demonstrates excellent molecular orientation, with electron density concentrated on sulfonate groups, forming a dipole. Gaussian calculations confirm that these negatively charged groups adsorb onto the ITO surface, establishing a favorable orientation for hole extraction. X‐ray photoelectron spectroscopy (XPS) measurements verified a stronger ITO interaction compared to PEDOT:PSS, enhancing hole extraction efficiency. With an ultralow activation energy of 1.37 meV, s ‐PEDOT:POM brings about a substantially enhanced conductivity of 1.08 × 10 − 3 S m − 1 . These enable OSCs with a PB3:FTCC‐Br: BTP‐CY active layer to achieve a record 81.36% Fill Factor (FF) and 20.35% Power Conversion Efficiency (PCE). Electrostatic repulsion also improves solution stability, with devices maintaining 96.34% initial efficiency after 1224 h storage, offering a scalable strategy for high‐performance, additive‐free PEDOT derivatives.