Microarray Formation Maximizes Quantum Dot Color Conversion

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BEIJING, June 16, 2022 — To enhance the color conversion process of quantum dots for use in LEDs, micro-LEDS, near-field displays, and other devices, researchers from Beijing Institute of Technology have developed perovskite quantum dot (PQD) microarrays. The assembly strategy aims to overcome a common problem facing conventional quantum dot color conversion (QDCC) pixels that are fabricated by inkjet printing: the thinness of the pixels preventing the dots from achieving efficient color conversion.

QDCC is a foundational technology in the design of full-color light-emitting devices, due to the ability of the technique to improve color performance. It additionally provides a wide range of color performance and easy integration. In printing, it can be used to achieve full-color OLEDs and micro-LEDs.

However, the conventional combination of quantum dots and coffee-ring effects, or puddle of particle-laden liquid that occur after evaporation, lowers the light conversion efficiency and emission uniformity in quantum dot microarrays. This also contributes to blue-light leakage or optical crosstalk, where unwanted coupling occurs between signal paths.

A research team has developed perovskite quantum dots microarrays with strong potential for QDCC applications, including photonics integration, micro-LEDs, and near-field displays. Courtesy of Nano Research, Tsinghua University Press.
A research team has developed perovskite quantum dots microarrays with strong potential for QDCC applications, including photonics integration, micro-LEDs, and near-field displays. Courtesy of Nano Research, Tsinghua University Press.
PQDs hold potential as an attractive material and can resolve some of the problems found in conventional QDCC, according to the researchers. While perovskite quantum dots are a relatively new technology, they have already been shown to be suitable for electronic and optoelectronic applications. By using patterned black photoresist molds to make QD pixels, researchers increased pixel thickness to avoid optical crosstalk to achieve better printing results.

“To solve these problems, we fabricated 3D perovskite quantum dots microarrays by combining the inkjet printing and in situ fabrication of perovskite quantum dots during the photopolymerization of precursor ink,” said Gaoling Yang, an assistant professor in the School of Optics and Photonics at Beijing Institute of Technology. Inkjet printing features noncontact, material-efficient, and reproducible processing. As a result, it has attracted attention in patterned microarrays.

Using photopolymerization, the researchers achieved a PQD color conversion microarray with a pixel size of 20 μm. The fabricated microarrays achieved strong and uniform photoluminescence in large area because of the seamless integration with in situ-fabricated PQDs. The researchers’ technique demonstrated the potential use of the in situ direct print photopolymerization method for fabricating patterned multicolor PQD microarrays with a wide color gamut and high resolution.

Additionally, the PQD microarrays exhibit characteristics that are desirable for QDCC applications including 3D morphology, the researchers said.

The research was funded by the National Key Research and Development Program of China, the National Natural Science Foundation of China, and the Beijing Institute of Technology Fund Program for Young Scholars Research.

The research was published in Nano Research (

Published: June 2022
The attribute of visual experience that can be described as having quantitatively specifiable dimensions of hue, saturation, and brightness or lightness. The visual experience, not including aspects of extent (e.g., size, shape, texture, etc.) and duration (e.g., movement, flicker, etc.).
quantum dots
A quantum dot is a nanoscale semiconductor structure, typically composed of materials like cadmium selenide or indium arsenide, that exhibits unique quantum mechanical properties. These properties arise from the confinement of electrons within the dot, leading to discrete energy levels, or "quantization" of energy, similar to the behavior of individual atoms or molecules. Quantum dots have a size on the order of a few nanometers and can emit or absorb photons (light) with precise wavelengths,...
Optoelectronics is a branch of electronics that focuses on the study and application of devices and systems that use light and its interactions with different materials. The term "optoelectronics" is a combination of "optics" and "electronics," reflecting the interdisciplinary nature of this field. Optoelectronic devices convert electrical signals into optical signals or vice versa, making them crucial in various technologies. Some key components and applications of optoelectronics include: ...
A process in which a mixture of one or more monomers, plus a catalyst, polymerize under exposure to light radiation. Photopolymerization permits a hologram to be exposed, fixed and reconstructed in about one-half second.
The term perovskite refers to a specific crystal structure commonly found in various materials. Perovskite structures have a cubic arrangement of oxygen ions, forming a framework within which other cations (positively charged ions) are located. This crystal structure was named after the mineral perovskite, which has the chemical formula CaTiO3 and was first discovered in the Ural Mountains of Russia. The general formula for the perovskite structure is ABX3, where: A represents a larger...
Photoluminescence is a phenomenon in which a material absorbs photons (light) at one wavelength and then re-emits photons at a longer wavelength. This process occurs when electrons in the material are excited to higher energy states by absorbing photons and subsequently return to lower energy states, emitting photons in the process. The emitted photons have less energy and longer wavelengths than the absorbed photons. Photoluminescence can be broadly categorized into two types: ...
Displayscolorquantum dotsLEDsOLEDsmicroLEDsnear fieldinkjet printingAsia PacificResearch & TechnologyeducationBeijing Institute of Technology optical crosstalkoptoelectronicsmicroarraysMaterialsphotopolymerizationcolor conversionperovskiteperovskite quantum dotsphotoluminescence

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