Efficient Quantum Dot Color Conversion Layer with Mixed Spherical/Rod-Shaped Scattering Particles

Abstract

A quantum dot (QD) color conversion layer (CCL) with mixed-shaped scattering nanoparticles exhibits enhanced light conversion and reduced blue leakage in QD-organic light-emitting diodes (OLEDs). In this study, nontoxic bright red QDs and spherical and rod-shaped zinc oxide (ZnO) nanoparticles were mixed in an ultraviolet-curable resin without aggregation. The mixture of spherical and rod-shaped ZnO nanoparticles enhanced the blue light scattering inside the QD CCL, which results in an increase of the blue absorption by the QDs and a dramatic improvement of the color conversion. Extraction of the converted red light was also attributed to the Mie scattering of the rod-shaped scattering nanoparticles. The QD CCL with 15 wt % mixed-shaped scattering particles showed seven times increase of red intensity and four times decrease of blue intensity compared to that without scattering particles. We fabricated direct coat-type QD-OLEDs and confirmed that the color conversion and output/input efficiencies were improved and the blue leakage was decreased with increasing number of QD CCLs. This method improves the color conversion efficiency without increasing the amount of QDs and reducing the blue leakage without using a color filter.

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

“…Beyond this point, increasing the concentration resulted in a gradual decline in PLQY. This decline can be attributed to the self-agglomeration phenomenon that occurs when the QD concentration is excessively high, which adversely impacts the PLQY [ 14 , 23 , 24 ]. Interestingly, the judicious addition of scattering particles such as TiO 2 can help alleviate this issue.…”

“…Additionally, they have a narrow full width at half maximum (FWHM), which can effectively enhance color purity and result in a broader color gamut. Hence, the integration of blue µ-LED s with QD color conversion technology is viewed as one of the effective alternatives today for overcoming challenges associated with RGB tri-color LED transfer technology [ 10 , 11 , 12 , 13 , 14 , 15 ]. In 2020, Kuo et al presented a full-color µ-LED fabricated from a semi-polar chip with a QD photoresist CCL [ 16 ].…”

“…One solution to this problem is to embed QDs into nano-porous µ-LED s, a structure that allows for QD accommodation and enhances light scattering, thus mitigating blue-light leakage [ 23 ]. Adding nanoscale scattering particles to elongate the light path, thereby boosting CCE and light intensity, is also a compelling strategy [ 14 , 17 , 24 ]. Common scattering particles include BN, SiO 2 , Al 2 O 3 , ZrO 2 , TiO 2 , and organic particles, among others.…”