CE09 - Nanomatériaux et nanotechnologies pour les produits du futur

Continuous flow synthesis of InP-based quantum dots – FLUO

Submission summary

Quantum dots (QDs) exhibit unique photophysical properties as narrow and size-tunable emission, broadband absorption and high fluorescence quantum yields (QY). Hence, QDs have already been integrated as color converters into the white backlight of LCD displays used in high-end television screens by companies such as Samsung. Because InP based QDs are in compliance with EU regulations (RoHS, REACH), they have been identified as the prime candidate for being the elemental building block for color conversion LEDs. Nevertheless, several challenges exist for improving the optical properties of InP-based QDs: (i) size distribution and emission line width; (ii) photoluminescence quantum yield (PL QY) photostability and (iii) large scale production with high reproducibility. The objective of this project is to tackle these issues and to validate the obtained InP-based QDs as color converters for the 3D (nanowire) blue LEDs developed by the industrial partner ALEDIA.
To improve the color purity of InP QDs, their size distribution needs to be greatly reduced. We propose two solutions: i) the use of combinations of novel indium and (non-pyrophoric) phosphorus precursors of controlled reactivity, to drive the reaction in the size-focusing regime; ii) the development of monodisperse clusters, which can be used in a seeded-growth approach, to control nucleation and growth independently, as the nuclei are supplied from an external source and not generated through homogeneous nucleation.
For enhancing the PL QY and photostability, the obtained QDs will be shelled using the “gradient shell approach”, which consists of generating a compositional gradient between the InP or InZnP core and the outer ZnS shell using appropriate intermediate shell materials (GaP and/or ZnSe).
To increase the reproducibility and to be able to produce high quality InP-based QDs on a larger scale, their continuous flow synthesis in tubular reactors will be developed. This technique enables a much better heat and mass transfer than traditional batch syntheses, paving the way for the reproducible precision synthesis of QDs. It also allows the high throughput screening of reaction parameters thanks to the inline in situ monitoring of the UV-vis absorption and PL properties of the QDs during the reaction. The obtained data gives access to the growth mechanism and enables the rational optimization of the reaction parameters.
The InP-based QDs will be integrated into acrylate-based transparent matrix materials to generate green and red pixels on ALEDIA wafer-type substrates, using photolithography to assist the deposition of each QD type on predefined zones. The obtained demonstrators for the color conversion of blue GaN nanowire based LEDs allow ALEDIA to assess the potential of InP-based QDs for integration in their technology.
The expected results are (i) high quality InP based QDs (Targeted specifications: PL emission at 530 and 620 nm (FWHM < 40 nm), PL QY > 80%), (ii) the first demonstration of continuous flow synthesis of InP-based core/shell nanocrystals and (iii) the implementation of these QDs into two and three color demonstrators evaluating the potential of the obtained QDs as color converters for blue light emitting III-V nanowire LEDs.

Project coordination

Peter REISS (Systèmes Moléculaires et nano Matériaux pour l'Energie et la Santé)

The author of this summary is the project coordinator, who is responsible for the content of this summary. The ANR declines any responsibility as for its contents.

Partner

ALEDIA ALEDIA
LPCNO LABORATOIRE DE PHYSIQUE ET CHIMIE DES NANO-OBJETS
SyMMES Systèmes Moléculaires et nano Matériaux pour l'Energie et la Santé

Help of the ANR 461,195 euros
Beginning and duration of the scientific project: December 2018 - 42 Months

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