Surface Passivation and Luminescence Mechanisms in InP Quantum Dots Toward High‐Efficiency and Stable QLED Emission

Indium phosphide (InP) quantum dots (QDs) have attracted significant attention as environmentally friendly luminescent nanomaterials for next-generation optoelectronic and display technologies because of their tunable optical properties and reduced toxicity. However, achieving high photoluminescence quantum yield, narrow emission linewidth, and long-term operational stability in InP-based QD light-emitting diodes (QLEDs) remains challenging. This review summarizes recent advances in the luminescence behavior and photophysical performance of InP QDs, with emphasis on surface passivation, multishell heterostructures, and interface engineering strategies that suppress defect-related nonradiative recombination. The effects of precursor chemistry, ligand dynamics, and shell architecture on emission efficiency, spectral purity, and optical stability are critically discussed. In addition, charge transport, exciton localization, and field-dependent recombination mechanisms are examined in relation to efficiency roll-off and spectral broadening under electrical excitation. Recent progress in high-brightness and narrow-linewidth InP/ZnSe/ZnS QDs is also highlighted together with current challenges associated with blue emission, interfacial degradation, and large-scale device integration. This review provides an integrated understanding of the luminescence mechanisms governing InP QDs and outlines future strategies for developing stable and highly efficient cadmium-free QLED systems.