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

This study presents a novel strain engineering strategy that enables stress relief and uniform shell growth at the InP quantum dot coreshell interface using a small-molecule Zn(Ac)₂ precursor. This approach significantly reduces interfacial strain and boosts the PLQY to nearly 100%. The resulting QLEDs demonstrate enhanced charge injection and energy level alignment, achieving an external quantum efficiency of up to 26.3%, offering a scalable platform for advanced quantum dot and device development.

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.

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