Dopant concentration controls reversible polarity switching in a single polymer semiconductor
A South Korean research team has discovered how to switch the charge polarity of an organic polymer semiconductor from p-type to n-type by precisely adjusting the concentration of a single dopant like gold(III) chloride (AuCl₃). This breakthrough, achieved for the first time at the molecular level, allows a single polymer to function as both hole and electron conductor, potentially simplifying device designs and enabling new flexible electronic applications.
A team led by Professor Kilwon Cho (POSTECH) and Professor Boseok Kang (Sungkyunkwan University) has demonstrated that varying the concentration of a dopant—specifically gold(III) chloride—reversibly switches the dominant charge carrier in an organic polymer semiconductor from positive (p-type) to negative (n-type). Using advanced analysis, the researchers revealed that this polarity switching is driven by a chemical process called substitutional chlorination, where gold and chloride ions interact with the polymer chains, inducing structural reordering and reorganization of charge transport pathways. This molecular-level mechanism not only clarifies how polarity reversal occurs but also enables the creation of high-performance p–n organic homojunction diodes from a single material. Such devices show rectification ratios orders of magnitude higher than conventional single-material organic diodes. By enabling both p-type and n-type conduction within a single polymer system, this approach eliminates the need for separate materials and complex device architectures, advancing the development of flexible, wearable, and stretchable electronics. The discovery marks a significant leap in the field of organic semiconductors, where achieving stable n-type behavior has long been a major challenge.
