Core technology developed for ultra-high-resolution quantum dot displays

A analysis crew has developed a direct optical lithography (DOL) technology that patterns quantum dots (QDs) at ultra-high decision utilizing solely mild, with out photoresist. Through this, in addition they offered pointers for deciding on cross-linkers important for fabricating high-performance QLEDs. This achievement is thought to be a core basic technology that may be utilized to a variety of optoelectronic units, together with micro-QLEDs, ultra-high-resolution displays, clear digital units, and next-generation picture sensors.

The paper is published within the journal Nano Letters. The research was led by Professor Jong-Soo Lee within the Department of Energy Science and Engineering at DGIST.

QDs are ultra-fine semiconductor particles about one hundred-thousandth the thickness of a human hair. Their emission colour might be freely tuned by measurement, thereby making them a next-generation show materials with excellent colour copy. However, typical photoresist-based patterning processes face limitations equivalent to advanced procedures, lowered emission efficiency, and sample deformation. In addition, inkjet printing and micro-contact printing are additionally constrained by way of decision and precision.

To deal with these limitations, the analysis crew launched a diazirine-based crosslinker, TDBA, which reacts to ultraviolet light (i-line, 365 nm). TDBA possesses each a “carboxylic acid functional group” that may straight bind to the floor of QDs and a diazirine construction that responds to mild.

With a single mild publicity, it chemically bonds to the QDs to type ultra-fine patterns. Using this strategy, the crew efficiently achieved ultra-high-resolution patterning at about 2 μm (6,350 DPI), whereas additionally making certain wonderful precision and stability.

In addition, following the patterning course of, the crew utilized post-treatment utilizing a thiol-based compound known as “PETMP,” which passivated floor defects on the QDs, thereby additional bettering their photoluminescence quantum yield (PLQY).

QLED units incorporating these post-treated QDs because the emitting layer achieved a most exterior effectivity of 10.3% and a most luminance of 99,369 cd/m², thereby demonstrating excellent machine efficiency. In addition, in semitransparent QLEDs using R/G/B QDs, they verified the feasibility of double-sided emission, thus opening up prospects for clear show functions.

In addition to growing the fabrication technology, the crew carried out an in-depth evaluation of how the molecular construction of cross-linkers impacts the optical and electrical properties of QDs.

By utilizing density useful concept (DFT), a quantum mechanical calculation technique, the crew in contrast TBBT, which incorporates sulfur (S) atoms, with BPDT, which doesn’t, and found that BPDT displays increased conductivity, making it extra advantageous for bettering QLED efficiency. This discovering is predicted to function an essential guideline for deciding on optimum supplies within the fabrication of high-resolution, high-performance QD displays.

Professor Lee acknowledged, “This research not only increases resolution, but also proposes a method for stable fabrication that preserves the intrinsic optical and electrical properties of QDs, along with clear criteria for material selection. We expect it will greatly accelerate the commercialization of next-generation displays such as AR and VR.”