Direct Synthesis of Highly Efficient NIR-I Emitting Core-Only InP Quantum Dots via Multiligand Synergy

Near-infrared (NIR) emission has garnered significant attention due to its broad applications in future optoelectronics. Among various candidates, indium phosphide (InP) quantum dots (QDs) have emerged as a promising option owing to their non-toxic composition and relatively facile synthesis. However, synthesizing NIR-emitting InP-based QDs with high luminescence efficiency remains a synthetic challenge, which is mainly attributed to the nucleation of a sufficiently large core and a complex shell process to achieve high-efficiency QDs. Herein, we present a direct synthetic strategy for NIR-I emissive core-only InP QDs with tunable emissions ranging from 683 to 742 nm through multiligand synergy. Under the competitive adsorption between ZnCl₂ and NH₄PF₆, InP QDs with sizes of approximately 6 to 10 nm are obtained within 5 minutes. In the multiligand environment, surface oxides are effectively removed by PF₆^-, and a negatively charged surface is established through the enrichment of zinc ions. This condition facilitates further adsorption and passivation of surface defects by short-chain NH₄⁺. The resulting core-only InP QDs exhibit bright NIR-I emission, achieving a quantum yield of up to 74%. Furthermore, the application potential of these core-only QDs is demonstrated through simple patterning. This work presents a straightforward, post-treatment-free synthetic strategy for high-performance core-only NIR-I InP QDs, highlighting their significant potential for practical applications in future optoelectronic devices.