Trioctylphosphine accelerated growth of InP quantum dots at low temperature.

Significant advance was realized on the economic synthesis of InP quantum dots (QDs) by using aminophosphines as phosphorus precursor. However, the low reaction activity and thermal degradation of aminophosphines bring severe difficulty for growth control of InP QDs. Here, we employed trioctylphosphine (TOP) as a surfactant to accelerate the growth of the InP QDs. The reaction mechanism study reveals that the TOP could form a reactive complex with indium halides that effectively accelerates the formation of InP monomer and reduces the demand for reaction temperature. On this basis, the effect of reaction temperature, precursors, and zinc halide additives on the growth of the TOP-InP QDs was explored. This strategy alleviates the difficulty in growth control of InP QDs and also benefits to the synthesis of luminescent InP/ZnS core-shell QDs within visible regime. A white-light emitting diode device was fabricated with the InP/ZnS QDs that demonstrates their application potential in light-emitting devices.

Low-temperature synthesis of tetrapod CdSe/CdS quantum dots through a microfluidic reactor.

Tetrapod CdSe/CdS quantum dots (QDs) have attracted extensive research interest in light-emitting applications due to their anisotropic optical properties and large absorption cross-section. Traditional synthesis methods for tetrapod CdSe/CdS QDs usually employ fatty phosphonic acid ligands to induce the growth of wurtzite CdS arms on cubic CdSe QDs at high temperatures (350-380 °C). Here, a low temperature (120 °C) route was developed for the synthesis of tetrapod CdSe/CdS QDs using mixed amine ligands instead of phosphonic acid ligands. A study of the growth mechanism reveals that the amine ligands induce the orientation growth of cubic CdS arms on wurtzite CdSe QDs through a pyramid-shaped intermediate structure. The low reaction temperature facilitates the growth control of the tetrapod CdSe/CdS QDs through a microfluidic reactor. This study substantially simplifies the synthetic chemistry for the anisotropic growth of CdS on CdSe QDs, paving the way for green and economic production of tetrapod CdSe/CdS QDs towards efficient light-emitting applications.

Efficient and Stable CdSe/CdS/ZnS Quantum Rods-in-Matrix Assembly for White LED Application.

CdSe/CdS core-shell quantum rods (QRs) are a promising prospect in optoelectronic applications but usually have a relatively low quantum efficiency and stability. Here, we report on an efficient and stable CdSe/CdS/ZnS QRs-in-matrix assembly (QRAs) by growing and embedding CdSe/CdS QRs in ZnS matrices. Structural characterizations show that the CdSe/CdS QRs are encapsulated and interconnected by ZnS in the QRAs structure. The stable ZnS encapsulation renders the CdSe/CdS QRs high quantum efficiency (QE) up to 85%. The QRAs also present high photo- and thermal-stability and can preserve 93% of the initial QE at 100 °C. The QRAs powder presents a light degradation of only 2% under continuous excitation for 100 h, displaying profound potential in optoelectronic applications. White light-emitting diodes (WLEDs) are fabricated by packaging the QRAs powder as phosphor on top of blue GaN chip. The WLED shows high optical performance and light quality.

Multi-quantum-well quantum dots with stable dual emission.

Multi-quantum-well quantum dots (MQW-QDs) with multiple emission peaks have been evaluated as promising single source emitters in the fabrication of high performance white LEDs. However, they still face a critical issue of color shift in practical applications, which is mainly attributed to the redistribution of the excitons between the adjacent wells under different excitation powers. Herein, we report sandwich structural MQW-QDs that provide highly stable dual emission. The study on the optical properties and exciton dynamics reveals that the thickness of the inner-barrier plays a crucial role in balancing the exciton distribution through regulating near-field energy transfer and light absorption between the adjacent wells. Meanwhile, the wells and the outer-barrier mainly influence the luminescence efficiency and the wavelength control of the dual emission peaks. The MQW-QDs with a minimum color shift versus excitation power are finally achieved by optimizing the structure parameters. A white LED based on the developed MQW-QDs exhibits a stable white light spectrum with high tolerance to the change of the excitation power, ensuring the advancement of the performance of MQW-QDs in lighting and display applications.

Synthesis of highly stable quantum-dot silicone nanocomposites via in situ zinc-terminated polysiloxane passivation.

Quantum dot (QD) silicone nanocomposites are promising luminescent materials for developing high performance light-emitting diodes (LEDs). However, their practical application still faces a critical issue of strong fluorescence quenching in commercial silicone, which is normally induced by the agglomeration of QDs and the impurities such as a Pt-catalyst and oxygen in the silicone matrices. This article reports the development of zinc-terminated polydimethylsiloxane (Zn-PDMS) to passivate CdSe/CdS/ZnS QDs via an in situ approach. The Zn-PDMS passivation protects the QDs from reacting with impurities and provides the mono-dispersion of QDs in silicone resin, leading to over 80% quantum efficiency as well as effective anti-quenching properties for the QD-silicone nanocomposite under an ambient atmosphere. A high performance warm-white LED prototype with direct on-chip packaging using the as-prepared QDs is developed.