Bright Red InP Quantum Dots via Mild Surface Etching with LiPF6

Eco-friendly indium phosphide (InP) quantum dots (QDs) with excellent optical properties are highly demanded for advanced display and lighting technologies. This work demonstrated a mild postsynthetic treatment method to enhance the optical properties of InP cores by utilizing lithium hexafluorophosphate (LiPF6) to remove POx– species from the core surfaces at nucleation temperature. This method avoided the use of toxic and corrosive hydrofluoric acid. The effects of LiPF6 dosage and treatment duration on the optical properties of InP cores were systematically investigated. After LiPF6 treatment, the photoluminescence quantum yield (PLQY) of the InP cores increased dramatically from <1 to 21%, with the removal of POx– species confirmed by XPS and FTIR analyses. Furthermore, the impact of LiPF6 introduction prior to shell coating on the properties of core–shell QDs with ZnSeS/ZnS shells was investigated. The introduction of LiPF6 induced a controlled emission red shift (from 614 to 620 nm) while dramatically boosting the PLQY from 62 to 90%. The fabricated light-emitting diode (LED), employing InP(F)/ZnSeS/ZnS QDs as color converters, achieved a maximum power efficiency of 1.11 lm W–1 with CIE coordinates of (0.702, 0.293). This work provides an efficient approach to optimize InP-based QDs for high-performance optoelectronic applications.