QD-EL

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. 

During Displayweek 2024, Samsung demonstrated its latest display prototypes, focusing mostly on flexible OLEDs, and QD-OLEDs.

The company also showed a 18.2" 3200x1800 (202 PPI) 250 nits QD-EL display, that was produced using an inkjet-printing process, based on cadmium-free QDs.

TCL CSoT demonstrated a 14" 2.8K inkjet-printed QD-EL display, that offers 30-120Hz VRR refresh rates and a 85% BT2020 color gamut. The impressive display won SID Displayweek's People's Choice Award.

TCL's CEO gave a keynote speech at Displayweek, saying how this is an early-stage technology that still has a lot of challenges before it can be commercialized - mainly the lifetime of the blue material. To encourage collaboration and innovation, TCL CSOT announced the Blue Star Project with a $1 million prize to incentivize collaboration and accelerate breakthroughs in QD-EL technology.

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.

DSCC says that the demand for QD materials in the display industry is growing, and the market will grow to $100 million in 2024. It will continue to grow and reach $122 million in 2027. 

The main application is in LCD displays (color conversion), but materials used in QD-OLED's (by Samsung Display) is growing and accounts for 31% of the market (in the chart above DSCC notes QD-OLEDs as QD-CC). Production of QD-OLED panels is limited (SDC's total capacity is for around 2 million panels per year) but the material usage is large compared to QD-LCDs.

Sharp was demonstrating two new QDEL prototype at CES 2024. The first was 12-inch in size (you can see this in the video below), and the second a 30-inch prototype (Sharp did not allow to take photos/videos of the larger display).

Sharp did not disclose much about the display, or any commercialization plans. This seems to be an early-stage development. We do know that Sharp is using QD materials produced by Nanosys (SHOEI), and that the display is produced on an IGZO (Oxide-TFT) backplane.

IDTechEx posted an article detailing the company's views on the quantum dot materials market for the display industry. The article details the progress from QD on Edge technology, to QDEF,  QDOG, QDCC and finally QLED displays (emissive QDs, or QD-EL).

IDTechEx believes that QDs are the "ultimate emissive material for displays", tracking efficiency and lifetime improvements. IDTechEx estimates that the global market for QD materials will reach $550 million by 2023 - this includes all QD applications, not just displays (but displays is one of the major markets).

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". 

Poland-based QNA Technology, a quantum dots developer and producer, raised $4 million in its latest financing round,and the company is now preparing to apply for a listing at the Polish ASO NewConnect stock exchange for early stage companies.

QNA was established in 2016, and is focused on blue light (400-490 nm) emitting, heavy metal-free quantum dots. The company optimizes its QDs for two applications: electroluminescence display devices (QD-EL) and for microLED displays devices based on UV microLEDs.