Large-Scale Synthesis of Highly Luminescent InP@ZnS Quantum Dots Using Elemental Phosphorus Precursor

Abstract

Colloidal quantum dots can control the bandgap by controlling the particle size, and are capable of solution processing, which is cost competitive, and has a narrow half width of the emission wavelength.Using these characteristics, it is possible to utilize various kinds of LED, solar cell, and bio imaging.Among them, indium phosphide (InP) quantum dots have a bandgap capable of emitting light in the near-infrared region from the visible light region, and are less toxic to humans and the environment than cadmium-based quantum dots, and are attracting attention as next generation light emitting materials.However, the limited choice and high cost of P precursors have a negative impact on their practical applicability. In this work, I report the large-scale synthesis of highly luminescent InP@ZnS QDs from an elemental P precursor (P4), which was simply synthesized via the sublimation of red P powder. The size of the InP QDs was controlled by varying the reaction parameters such as the reaction time and temperature, and the type of In precursors. This way, the photoluminescence properties of the synthesized InP@ZnS QDs could be easily tuned across the entire visible range, while their quantum yield could be increased up to 60% via the optimization of reaction conditions. Furthermore, possible reaction pathways for the formation of InP QDs using the P4 precursor have been investigated with nuclear magnetic resonance spectroscopy and it was demonstrated that the direct reaction of P4 precursor with In precursor produces InP structures without the formation of intermediate species. The large-scale production of InP@ZnS QDs was demonstrated by yielding more than 6 g of QDs per onebatch reaction.In the case of InP using different precursor P except the Tris(Trimethylsilyl) phosphine ((TMS)3P) there has been a problem that the size distribution is poor. Two kinds of P precursors with different reactivities were used to separate the nucleation and growth processes and to induce growth along the Lamer mechanism to produce uniform particles. For this, (TMS)3P and DEAP were used as fast reacting P precursors, and P4 was used as a slow reacting P precursor. Through this, the possibility of uniform particle formation was observed. I strongly believe that the newly developed approach bears the potential to be widely used for manufacturing inexpensive high-quality QD emitters. Blank page Contents

Flexible quantum dot light-emitting diodes for next-generation displays

“…[63][64][65][66] Although there have been several reports on InP QLEDs, a gap remains in terms of the performance of InP QLEDs and that of Cd-chalcogenide QLEDs, 67,68 which can be attributed to the lack of fundamental understanding of the EL process of InP QDs. Recent progress on QLEDs based on green InP core-shell QDs is encouraging (Fig.…”

High‐Efficiency Green InP Quantum Dot‐Based Electroluminescent Device Comprising Thick‐Shell Quantum Dots

“…Among all of the heavy metal‐free fluorescent QDs, indium phosphide (InP) QDs are one of the most promising candidate materials for light‐emitting applications to replace the Cd‐based QDs due to their low intrinsic toxicity, stable and tunable narrow emission from visible to near‐infrared region . At present, the performance of InP core/shell QDs‐based LED remains far lower than those Cd‐ or Pb‐based ones, which is the bottleneck for further practical application of InP‐based devices.…”

Multistage Microfluidic Platform for the Continuous Synthesis of III–V Core/Shell Quantum Dots

“…By alternating injections of additional molecular precursors into the third microreactor, we managed to obtain InP QDs exhibiting band‐edge absorption up to 595 nm with precise control. Preparation of larger InP cores (band‐edge absorption higher than 600 nm) remains a synthetic challenge . In this work, we introduced extra myristic acid to overcome the growth limitation, which simultaneously promotes the ripening of nanoparticles and broadens particle size distribution.…”

“…Therefore, multistep synthesis is commonly employed to prepare III‐V QDs in a sequential manner . Additionally, to improve the stability and brightness of III‐V QDs, higher band gap materials, such as ZnS and CdS, are often used, which can passivate the surface sites of III‐V QDs . As a result, to transfer this multistep synthesis of III‐V core/shell QDs to continuous nanomanufacturing, we need to develop multistage high‐temperature reactors with consecutive reaction steps.…”