Deep-Red InP Core-Multishell Quantum Dots for Highly Bright and Efficient Light-Emitting Diodes

InP-based quantum dots (QDs) are one of the most promising heavy-metal-free materials for light-emitting applications to substitute cadmium-analogous QDs. With a bulk band gap of 1.35 eV, InP QDs can be made to emit light in the deep red and even near-infrared region by adjusting the size. Deep-red light-emitting diodes (LEDs) are of great interest for promoting the growth of plants and accurate red LED displays. However, the synthesis and the fabrication of InP-based quantum-dot LEDs (QLEDs) emitting in the deep red region are still under development. Here, the study reports deep-red InP/ZnSe/ZnSeS/ZnS core-shell QDs with a photoluminescence (PL) emission peak at 680 nm and a PL quantum yield up to 95%, which is the highest among reported deep-red QDs. Multi-shell with a transition layer of ZnSeS is realized to decrease the lattice mismatch in the shell and increase the shell thickness, which efficiently confines charge carriers and reduces non-radiative recombinations. In addition, the core-shell InP QLED achieves a high luminescence of 2263 cd m⁻² and an external quantum efficiency up to 6.5%. This report provides a new strategy for promoting the development of deep-red QLEDs for next-generation lighting and display devices.