Dual-functional Cr3+-doped InP quantum dots with pure blue emission and room-temperature ferromagnetism

Indium phosphide (InP) quantum dots (QDs) have gained global research focus owing to their eco-friendly properties and outstanding optical characteristics. However, blue emission of InP QDs has made slow progress owing to surface defects and lattice mismatch between core and shell. Meanwhile, the ferromagnetism of traditional dilute magnetic semiconductors (DMSs) is limited by insufficient Curie temperature, failing to meet practical applications. Herein, we report Cr 3+ -doped InP/ZnS QDs with dual functions of pure blue emission and room-temperature ferromagnetism. By using hot injection method, Cr 3+ ions are precisely embedded into the core-shell interface of QDs, effectively passivating the surface defects of the InP cores. This approach enables the fabrication of pure blue-emitting QDs with an emission of 471 nm, a photoluminescence quantum yield (PLQY) of 52%, and a full width at half maximum (FWHM) of 46 nm. Through the dominance of ferromagnetic superexchange interaction, synergizing with the intrinsic strong local magnetic moment of Cr 3+ and quantum confinement effect, room-temperature ferromagnetism is achieved in InP-based QDs for the first time (Curie temperature above 350 K and maximum coercivity of 95.45 Oe). This work provides new materials for spintronic devices, and the Cr 3+ doping strategy also offers a reference for the opto-magnetic regulation of III-V QDs. This research first achieved a breakthrough in room-temperature ferromagnetism and efficient blue emission in InP QD system. Cr:InP/ZnS QDs with emission wavelength of 471 nm and PLQY of 52% are prepared. Through the dominance of ferromagnetic superexchange interaction, room-temperature ferromagnetism is first realized in InP QDs • Cr 3+ ions embedding in core-shell interface enables 471 nm pure blue emission via passivating the P dangling bonds. • Room-temperature ferromagnetism with a Curie temperature exceeding 350 K is realized in InP-based QDs for the first time. • Provides new materials for spintronics and doping strategy for opto-magnetic regulation of III-V QDs.