Theoretical Investigation of Organic Ligands on the Surface Structure of InP Quantum Dots: Implications for Display Materials with Enhanced Surface Stability

InP quantum dots (QDs) have emerged as a prominent luminescent material for display applications owing to their tunable emissive properties and reasonable stability attributed to nanoscale surface characteristics. However, the surface structures of InP QDs remain elusive primarily due to the influence of organic ligands that dynamically interact with surface atoms, ultimately affecting the surface stability. In this study, we comprehensively explore the structural features and energetics of InP QD surfaces modified by carboxylate and phosphine ligands, employing both slab and wedge models in theoretical investigations. The carboxylate ligand exhibits diverse binding modes, including various types of bidentates and even monodentates, on the surface of In atoms and effectively stabilizes polar facets. Conversely, the phosphine ligand acts as a stabilizer for the nonpolar facet. As a result, the equilibrium shape of InP QDs is anticipated to comprise multiple facets, unveiling the presence of the dominant (111) facet alongside the (100) and (110) facets. To validate our theoretical predictions, we obtained the projected shapes of the synthesized InP QDs using aberration-corrected high-resolution scanning transmission electron microscopy. The experimental observations confirm our modeling predictions, reinforcing the accuracy of our findings.