Dopant Threshold Triggers Polarity Inversion in Polymers
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- Boseok Kang's team at Sungkyunkwan University identified that polarity inversion in polymer semiconductors requires dopant uptake to exceed a critical threshold set by the material's molecular structure.
- Once that threshold is crossed, dopant-derived anions interact strongly with the polymer, switching charge transport from p-type to n-type — a transition that does not occur when dopant absorption remains insufficient.
- Yun-Hi Kim (Gyeongsang National University) and Han-Sol Lee (Gachon University) collaborated on the study, published in Advanced Functional Materials (2026) with DOI 10.1002/adfm.202522164.
- The finding explains a long-standing puzzle: polarity inversion has appeared in only a limited number of polymers despite similar doping conditions across many systems.
- Polarity inversion enables both p-type and n-type behavior within a single material, which simplifies device structures and improves manufacturing efficiency for flexible, solution-processable printed electronics.
- Prof. Kang cautioned that current device performance remains at an early stage and that further improvements will require optimization of both molecular design and device architecture.
Why it matters: For materials scientists designing organic semiconductors, this finding reframes the central design question from doping intensity to molecular architecture that controls dopant uptake — potentially enabling single-material devices that switch between p-type and n-type behavior and reducing manufacturing complexity for next-generation flexible printed electronics.
