Direct synthesis of highly efficient NIR-I emitting core-only InP quantum dots via multi-ligand synergy

Near-infrared (NIR) emission has garnered significant attention owing to its broad application potential in next-generation optoelectronics. Among various candidates, indium phosphide (InP) quantum dots (QDs) have emerged as particularly promising candidate due to their environmentally benign composition and relatively facile synthesis. However, the synthesis of NIR-emitting InP-based QDs exhibiting high luminescence efficiency remains a critical challenge. The inherent difficulties primarily stem from insufficient core nucleation and the complex shell growth processes essential for achieving high-performance QDs. Herein, we report an expeditious synthetic strategy for achieving NIR-I emissive core-only InP QDs with tunable emission ranging from 683 to 742 nm, mediated by the synergistic effect of ZnCl 2 and NH 4 PF 6 . Under the competitive adsorption between ZnCl 2 and NH 4 PF 6 , high-covalent InP QDs with sizes of approximately 6 to 10 nm can be obtained within 5 min. During the later stages in this dual-salt system, PF 6 − effectively eliminates surface oxides while zinc ion enrichment establishes a negatively charged surface. This Zn-related configuration promotes subsequent adsorption and defect passivation by NH 4 + . The final core-only QDs exhibit bright NIR-I emission with a photoluminescence quantum yield of up to 74 % in solution. Furthermore, the application potential of these core-only QDs is demonstrated through simple patterning. This work establishes a straightforward, post-treatment-free synthesis of high-performance NIR-I core-only InP QDs, highlighting their substantial promise for next-generation optoelectronic devices.