Freestanding High-Resolution Quantum Dot Color Converters with Small Pixel Sizes

Abstract

Designing the next generation of high-resolution displays requires high pixel density per area and small pixel sizes without compromising the optical quality. Quantum dots (QDs) have been demonstrated as a promising material system for down-conversion of blue emission as they provide pure colors on the wide color gamut. However, for high color-conversion efficiency, the required QD film thickness has not been compatible with small pixel sizes. In this work, we develop a new type of freestanding QD-based color converter for efficient optical down-conversion from inorganic blue light-emitting diodes (LEDs) in a color-by-blue configuration. CdSe/ZnS core–shell QDs in a UV-curable polymer matrix are encapsulated within cavities formed by patterning and bonding a pair of patterned quartz substrates. By controlling the required QD thickness and the pixel size independently, we demonstrate freestanding monochrome red and green converters with small pixel sizes down to 5 × 5 μm2 and a high resolution of >3600 ppi. The optical studies show that the QD film thickness required for efficient color conversion can be successfully realized even for the small pixel sizes. We further combine green and red pixels in a single converter to achieve white emission when combined with blue LED emission. The QD color converter design and processing are decoupled from the LED fabrication and can be easily scaled to wafer-size integration with arbitrary pixel sizes for QD-based RGB displays with ultrahigh resolution.

Patterning Quantum Dots via Photolithography: A Review

“…Mixing QDs with photosensitive materials, such as PR, is a simple method for fabricating photopatternable QD films. [92][93][94][95][96][97][98][99][100] Because the technical strategy for the high-resolution patterning of PR is well developed, highly luminescent QD-PR composite patterns should be formed directly via photolithography by employing commercial PR. Because photolithography is a welldeveloped technique, a controllable thickness and fine patterning capability can be achieved for highly luminescent QD-PR composite patterns.…”

Direct Photolithography Patterning of Quantum Dot‐Polymer

“…As the easiest of the three bonding methods to realize, QD-Polymer formed by polymer-coated QDs is usually simply a blend of the photosensitive polymer monomer and QDs. [58][59][60][61][62][63][64][65][66][67][68][69][70] Therefore, it can be adapted to most experimental environments and allows for easier control of pattern parameters by direct photolithography. Many studies have indicated that numerous photosensitive polymers available in the market can be uniformly mixed with QDs.…”

All-inorganic lead halide perovskite nanocrystals applied in advanced display devices

“…27,28 Each light-emitting unit in a large-area region can be controlled independently in this kind of technology resulting in high-contrast displays, and high-quality luminous materials help to realize the high-purity color and the wide color gamut. 29–31 But the industry procedure and technology are not mature now, and they still face problems in realizing both stable materials and low-cost manufacturing.…”