A New PEDOT Derivative for Efficient Organic Solar Cell with a Fill Factor of 0.80

Abstract Although PEDOT:PSS is the most prominently used conducting polymer as hole transporting layer (HTL) material in organic solar cells (OSCs), the strong acidity of PEDOT:PSS has been proved to cause corrosion on electrodes, which is largely responsible for device instability. At present, the development of a non‐corrosive and stable PEDOT with comparable performance to PEDOT:PSS remains a great challenge in the field. Herein, a solid n ‐PEDOT:POM powder with neutral pH is synthesized by utilizing polyoxometalate (POM) as an oxidizing reagent, which exhibits excellent water solubility, high chemical stability, and superior hole collection ability. Impressively, an amazing fill factor of 0.80 along with a photovoltaic efficiency of 17.62% is obtained in the OSC by using n ‐PEDOT:POM as the HTL, suggesting an exceptional hole collection ability for n ‐PEDOT:POM. In addition, the neutral pH of PEDOT:PSS effectively improves the long‐term stability of OSCs. X‐ray photoelectron spectroscopy results reveal that, compared to the electrode/PEDOT:PSS interface, the permeation of dissociative indium from the electrode to n ‐PEDOT:POM can be greatly retarded, which proves the non‐corrosive effect of n ‐PEDOT:POM and its improvement of device stability. The successful preparation of a non‐corrosive and stable PEDOT derivative without sacrificing its hole collection ability provides the most fruitful new insight into developing high‐performance HTL materials.