Technical / research

Researchers from Korea's Daegu Gyeongbuk Institute of Science and Technology (DGIST) developed a stretchable QD color conversion layer, that can be used in stretchable microLED displays. These QD films use a technology developed at DGIST that enables the direct linkage of quantum dots.

The researchers say that the color-conversion layer delivers high color reproducibility while maintaining performance even when stretched by more than 50%.  The color-conversion layer fabricated with this technology achieved a high resolution of 313 PPI.

Researchers from Korea's Daegu Gyeongbuk Institute of Science and Technology (DGIST) developed a new way to pattern QDs, using direct optical lithography (DOL). DOL can be used to pattern QDs with ultra-high resolutions - without any photoresist.

In addition to developing this method, the researchers provided guidelines for selecting cross-linkers essential for fabricating high-performance QLEDs. 

Researchers from North Carolina State University developed multi-robot self-driving laboratory that autonomously discovers high-performance quantum dots. The "Rainbow Lab" can conduct and analyze up to 1,000 experiments per day without human intervention, dramatically accelerating the pace of materials discovery.

The researchers say that the robots automatically prepare chemical precursors, mix them, and execute multiple reactions in parallel using miniaturized batch reactors – up to 96 reactions at a time. The system then automatically transfers all reaction products to a characterization robot, which analyzes the outcomes. From start to finish, every step is fully automated and intelligently coordinated.

Researchers at China's Ningbo University have introduced two key molecular additives into CsPbBr₃ perovskite quantum dots (PeQD) inks: an organic pseudohalide, dodecyl dimethylthioacetamide (DDASCN), and a photosensitive ligand, pentaerythritol tetrakis(3-mercaptopropionate) (PTMP).

With this synergistic strategy, the team fabricated fully solution-processed green perovskite QLEDs that achieved a maximum luminance of 30,500 cd/m² and an external quantum efficiency of 18.6%, ranking among the highest reported for solution-processed perovskite QLEDs.

Researchers from Sungkyunkwan University developed a source material for the inorganic hole transport layer of QD-EL devices. The researchers say that the new material significantly enhances the brightness and stability of emissive QD displays.

The researchers say that currently used organic HTL materials suffer from low conductivity and thermal instability. The new material is a standard HTL doped by defect-controlled nickel oxide-magnesium oxide alloy and treated with magnesium hydroxide. Using the new material, the EQE of the QD-EL device increased to 16.4%. The doping and treatment lowered the hole conductivity of the hole transport layer and suppressed the hole extraction process from within the quantum dots, thereby enhancing the device efficiency to a level comparable to existing technologies.

Researchers from China's Southern University of Science and Technology, by simultaneously measuring the electroluminescence-photoluminescence, have identified the presence of leakage electrons in QD-EL devices, which leads to the discrepancy of the electroluminescence and the photoluminescence roll-off.

The researchers then developed a single photon counting technique, the enables them to detect the weak photon signals and thus provides a means to visualize the electron transport paths at different voltages. By reducing the amount of leakage electrons, the researchers developed a QD-EL device with an internal power conversion efficiency of over 98%.

Researchers at Daegu Gyeongbuk Institute of Science and Technology (DGIST), Ulsan National Institute of Science and Technology (UNIST), and the Institute for Basic Science (IBS) have developed a new method, called double-layer dry transfer printing, to create highly efficiency QD-EL displays.

The researchers say that with the double-layer dry transfer printing technique, the light-emitting and electron-transferring layers of the device can be transferred onto a substrate simultaneously, which reduces interfacial resistance in the device, which facilitates electron injection and the control of leakage charge transport during the fabrication process. The researchers, by minimizing the leakage current, managed to increase the EQE of the QLED device to 23.3%, up from around 5% that is achieved with normal dry transfer printing. 

Researchers from Korea's Institute for Basic Science, led by Professor KIM Dae-Hyeong, published a new article in Nature that details intrinsically stretchable quantum dot LEDs. 

The researchers say that using current technology, making stretchable light-emitting devices results in poor luminous performance. The researchers now produced the intrinsically stretchable QD-LEDs using a mechanically soft and stretchable emissive layer consisting of a ternary nanocomposite of colloidal quantum dots, an elastomeric polymer and a charge transport polymer.

The prestigious Nobel Chemistry prize for 2023 was awarded to Moungi Bawendi, Louis Brus and Aleksey Ekimov, the three scientists that discovered quantum dots.  The Nobel prize is worth 11 million Swedish crowns (around $1 million), and will be split between the 3 winners.

The Royal Swedish Academy of Sciences, that awards the prize, stated that "Researchers believe that in the future they (QDs) could contribute to flexible electronics, tiny sensors, thinner solar cells and encrypted quantum communication".

Researchers from MIT have devised a new method to precisely assemble arrays of quantum rods, using scaffolds made of folded DNA. Using this method, the orientation of the rods can be controlled, which is a key factor in determining the polarization of light emitted by the quantum rods array.

The method starts by attaching the quantum rods to diamond-shaped DNA origami structures, built at an exact size required by the device. The structures are then attached to a surface, where they fit together "like puzzle pieces".