InP-Based Quantum Dot Photonic Devices

Indium phosphide (InP) quantum dots (QDs) have emerged as leading candidates for heavy-metal-free photonic applications, offering tunable emission across the visible spectrum with reduced toxicity compared to cadmium-based systems. The intrinsic bandgap of InP enables size-dependent colour control, while the addition of tailored inorganic shells—such as ZnS, ZnSe or GaP layers—serves to passivate surface traps, improve photoluminescence quantum yields and enhance stability under optical and electrical excitation. Core–shell and core–shell–shell heterostructures address lattice-mismatch strain and mitigate non-radiative recombination pathways, crucial for high-performance light-emitting diodes (QLEDs), display backlighting and integrated photonic circuits. Recent advances have tackled challenges of oxidation-induced defect formation, energy-level alignment for balanced carrier injection and the engineering of type-I versus type-II band alignments to optimise emission colour purity and device efficiency. With ongoing progress in synthetic control and photonic integration, InP-based QDs are poised for widespread adoption in next-generation lighting, displays and optical communication platforms.

Research from Nature Portfolio

Recent investigations into InP/ZnSe/ZnS core–shell quantum dots have elucidated how UV-facilitated oxidation induces surface oxide formation, dislocation defects and interfacial strain that promote indium diffusion from the core, ultimately quenching emission. High-resolution transmission electron microscopy reveals the pathways by which shell morphology evolves under photo-oxidative stress, informing strategies for more robust surface architectures. In a complementary study, a heating-up synthetic approach for InP/GaP/ZnS core–shell–shell QDs delivered reproducible full-colour emission across the visible range through controlled precursor injection and shell-growth kinetics. This method achieved high quantum yields and narrow emission bandwidths by tuning precursor reactivity and shell composition, laying the groundwork for scalable production of colour-tunable, heavy-metal-free QDs.

Research from all publishers

Engineering of inner alloyed shells in green-emitting InP QLEDs, achieved by inserting gradient ZnSexS1–x layers, has led to the highest reported pure-green external quantum efficiencies. The graded shell reduces lattice mismatch, passivates interfacial defects and aligns energy levels to balance electron and hole injection, yielding narrow emission profiles with quantum yields approaching unity. Another significant development demonstrated cadmium-free type-II InP/ZnO/ZnS core–shell–shell QDs with a peak photoluminescence quantum yield of ~91%. When employed as down-converters on blue LED chips, these QDs delivered an external quantum efficiency of 9.4% and a power conversion efficiency of 6.8%, highlighting their promise for efficient, non-toxic QLED architectures and solid-state lighting.

InP-Based Quantum Dot Photonic Devices publication trend

The graph below shows the total number of articles in inp-based quantum dot photonic devices across all publications each year (not limited to Nature Index journals).

Technical terms

Quantum dot (QD): A semiconductor nanocrystal that confines electrons and holes in three dimensions, producing size-tunable optical emission.

Core–shell structure: A nanoparticle design in which an inner semiconductor core is overcoated with one or more inorganic shells to passivate surface defects and improve stability.

Photoluminescence quantum yield (PLQY): The ratio of emitted photons to absorbed photons, serving as a measure of radiative efficiency.

Quantum dot light-emitting diode (QLED): An optoelectronic device using quantum dots as the emissive layer to produce high-colour-purity light under electrical drive.

External quantum efficiency (EQE): The proportion of injected charge carriers that are converted into emitted photons in a light-emitting device.

Type-II heterostructure: A core–shell configuration where the conduction band minimum and valence band maximum reside in different materials, promoting spatial separation of charge carriers.

References

1. Insights into structural defect formation in individual InP/ZnSe/ZnS quantum dots under UV oxidation. Nature Communications (2024).
2. Highly luminescent InP/GaP/ZnS QDs emitting in the entire color range via a heating up process. Scientific Reports (2016).
3. Highly efficient green InP-based quantum dot light-emitting diodes regulated by inner alloyed shell component. Light: Science & Applications (2022).
4. Cadmium-Free and Efficient Type-II InP/ZnO/ZnS Quantum Dots and Their Application for LEDs. ACS Applied Materials & Interfaces (2021).