Ameliorating Uniformity and Color Conversion Efficiency in Quantum Dot-Based Micro-LED Displays through Blue–UV Hybrid Structures

Abstract

Quantum dot (QD)-based RGB micro light-emitting diode (μ-LED) technology shows immense potential for achieving full-color displays. In this study, we propose a novel structural design that combines blue and quantum well (QW)-intermixing ultraviolet (UV)-hybrid μ-LEDs to achieve high color-conversion efficiency (CCE). For the first time, the impact of various combinations of QD and TiO2 concentrations, as well as thickness variations on photoluminescence efficiency (PLQY), has been systematically examined through simulation. High-efficiency color-conversion layer (CCL) have been successfully fabricated as a result of these simulations, leading to significant savings in time and material costs. By incorporating scattering particles of TiO2 in the CCL, we successfully scatter light and disperse QDs, effectively reducing self-aggregation and greatly improving illumination uniformity. Additionally, this design significantly enhances light absorption within the QD films. To enhance device reliability, we introduce a passivation protection layer using low-temperature atomic layer deposition (ALD) technology on the CCL surface. Moreover, we achieve impressive CCE values of 96.25% and 92.91% for the red and green CCLs, respectively, by integrating a modified distributed Bragg reflector (DBR) to suppress light leakage. Our hybrid structure design, in combination with an optical simulation system, not only facilitates rapid acquisition of optimal parameters for highly uniform and efficient color conversion in μ-LED displays but also expands the color gamut to achieve 128.2% in the National Television Standards Committee (NTSC) space and 95.8% in the Rec. 2020 standard. In essence, this research outlines a promising avenue towards the development of bespoke, high-performance μ-LED displays.

InGaN-based Blue Resonant Cavity Micro-LED Combined with Red-Green-Yellow Quantum Dot Color Conversion Layer for Wide Color Gamut and Energy- Efficient Full-Color Displays

“…This improvement is crucial for the development of high-performance displays and optical devices. Commonly used nanoscattering particles include titanium dioxide (TiO 2 ) [13,22], zirconium dioxide (ZrO 2 )[26, 27], silica (SiO 2 ) [23], and aluminum oxide (Al 2 O 3 )[28], among others. These particles are selected for their high refractive index, chemical stability, and favorable optical properties, which effectively scatter visible light and boost the luminous e ciency of QDs.…”

“…In previous research, we explored the advantages of adding TiO 2 scattering particles in QDPR using simulation software and con rmed that the addition of an appropriate amount of scattering particles can help improve the LCE. [13,[21][22][23] In this study, we speci cally delve into the reliability aspect. Figure 2 compares green QDPR thin lms without scattering particles, with ZrO 2 added, and with TiO 2 added, respectively.…”

“…Due to the self-aggregation effect of QDs, the uniformity of illumination in yellow light photolithography processes for QDs is usually poor. [13] By adding nano-scattering particles into the QD ink, the light scattering effect is ampli ed, increasing the possibility of blue light stimulating the QDs.…”

“…Besides achieving higher color conversion e ciency, it also effectively enhances color purity, yielding a broader color gamut area, making it highly suitable as a color conversion layer (CCL). [12][13][14][15][16][17] Combining blue RCLED with red, green, and yellow CCLs achieves high directionality and precise wavelength control, helping to reduce optical crosstalk between different color pixels, thus enhancing color purity and display clarity.…”

“…However, as display devices continue to become thinner and smaller, QD CCLs, when insu cient in thickness, tend to leak a signi cant amount of blue light, leading to a substantial drop in light conversion e ciency (LCE). [17] To address this issue, embedding QDs in nanoporous Micro LEDs can accommodate QDs [18][19][20] and increase light scattering [13,[21][22][23], improving the issue of blue light leakage. Additionally, adding nano-sized scattering particles to extend the light path is an excellent solution for enhancing LCE and light intensity.…”