Dual‐Mode Strain Relief via Zinc Acetate Enables High‐Efficiency InP Quantum Dot Light‐Emitting Diodes

Abstract Heteroepitaxial shell growth on quantum dots (QDs) is essential for tailoring carrier dynamics but is often hampered by core–shell interface strain, which becomes more prominent in environmentally friendly InP QDs due to their significant size effect. Although post‐treatment of InP cores with zinc compounds is a common approach to alleviate interface strain, conventional synthesis methods often fail to achieve effective doping, typically leaving zinc on the core surface rather than within the lattice. Herein, we present a dual‐mode strain relief strategy using the small‐molecule precursor Zn(Ac) 2 . Its ionic bonding character and low steric hindrance enable efficient Zn doping into the InP core and promote uniform epitaxial shell growth, leading to a 50% reduction in interfacial strain and a near‐unity photoluminescence quantum yield in InP QDs. This approach simultaneously addresses two major sources of strain: lattice mismatch between the core and shell and steric hindrance from bulky surface ligands. The fabricated green InP‐based QLED achieved a high external quantum efficiency of 26.3% and a current efficiency of 108.3 cd A −1 . We believe this strategy provides a general and scalable strain engineering platform for QDs, with broad applicability across various material systems.