Ion‐Precise Electrosynthesis and Memristors of Sequence‐Controlled Conjugated Polymers

ABSTRACT The ion‐precise synthesis of polymer materials remains a challenge because of the counterion exchange during solution‐processed synthesis and processing. Here, we demonstrate ion‐precise electrosynthesis and memristors based on conjugated polymers, in which both backbone cations and counteranions are sequence‐controlled for the first time. Inter‐ and intramolecular counterion exchanges are effectively blocked during surface‐initiated growth of crystalline polymer monolayers, enabling us to distinguish a correlation between a library of sequence‐controlled cationic conjugated polymers and their counteranions, as well as their intrinsic negative differential resistance (NDR). We find that controlled anion migration is a key factor in achieving ultralow NDR bias in redox‐based memristors, dramatically reducing it from 1.75 V to a record low of 0.13 V. The peak‐to‐valley current ratio (PVCR) reaches 117 at 0.55 V, demonstrating a strategy that achieves a giant PVCR while simultaneously maintaining a low NDR bias. Unlike previously reported usual single or rarely double NDR peaks, we observe triple NDR peaks, which are theoretically more advantageous for multivalued logic computing. Our work represents a paradigm shift toward high‐dimensional control of polymer structures within a two‐dimensional molecular system for ion‐precise memristors, while demonstrating advantages in tailoring intrinsic NDR beyond existing methods or materials.