Ligand polarization-driven surface rigid confinement for reliable perovskite quantum dot memristors

Ligand polarization effect directly targets the atomic origin of stochastic ion migration via surface rigid confinement. • Surface octahedra transition from disordered to ordered, rigid state, raising migration barrier from 0.28 eV to 0.42 eV • Two-order-of-magnitude enhancement in ON/OFF ratio with over 70% reduced voltage dispersion and stable operation beyond 10 4 s • Optimal polarization window enables four-level multilevel storage and boosts synaptic recognition accuracy from 71.8% to 90.6% Perovskite quantum dots (PQDs) memristors exhibit pronounced ion migration activity owing to their soft lattice nature. However, the surface octahedral disorder induced by this structural flexibility often leads to stochastic ion migration, limiting device reliability. Herein, we employ the ligand polarization effect to suppress this stochastic ion migration through surface rigid confinement. By anchoring a strong-dipole ligand onto the quantum dot surface, the electrostatic coupling between the molecular dipole field and surface defects reconstructs the surface coordination environment and stiffens the octahedral framework, elevating the vacancy migration activation energy from 0.28 eV to 0.42 eV and effectively suppressing ion migration at the quantum dot surface. Through this strategy, the memristors demonstrate a two-order-of-magnitude increase in on/off ratio (from 10 1 to 10 3 ), over 70% reduction in operating voltage dispersion, cycling endurance exceeding 2 × 10 3  cycles, and retention beyond 10 4  s, while maintaining stable resistance states for over 60 days under ambient conditions. Tuning the ligand polarization strength reveals an optimal polarization window, enabling four-level multilevel storage and elevating synaptic recognition accuracy from 71.8% to 90.6%. This work provides an effective ligand polarization-based strategy for suppressing ion migration at its origin in perovskite quantum dot memristors. A ligand polarization-assisted surface rigid confinement strategy is developed for suppressing stochastic ion migration in CsPbBr 3 quantum dot-based memristors. The strong-dipole ligand anchors onto the quantum dot surface, driving surface atom rearrangement through electrostatic coupling and forming a rigid confinement layer that stabilizes conductive filaments. The resulting memristors achieve a two-order-of-magnitude enhancement in ON/OFF ratio and stable resistive switching. As artificial synapses, these devices demonstrate improved synaptic plasticity and a recognition accuracy of 90.6%, outperforming the control device (71.8%). Download: Download high-res image (145KB) Download: Download full-size image