Dual Role of Quantum Dots as Color Conversion Layer and Suppression of Input Light for Full-Color Micro-LED Displays

Abstract

In micro-light-emitting diode (micro-LED) displays with colorconversion layers, a facile and efficient technology getting rid of the use of the color filters leads to a big technical leap in cost-effective fabrication. In this study, it is demonstrated that quantum dot (QD) color conversion layers can significantly suppress residual blue excitation light because of the high extinction coefficients of QDs, ∼0.1% transmittance of blue light for green and red core/shell CdSe/ZnS QD film with thickness of less than 17 μm, and produce green and red colors. Incorporation of TiO 2 nanoparticles into QD solutions enhances more than 10% of the luminous intensity by the scattering effect. It is found that the suppression of QD reabsorption is essential to achieve a high color-conversion efficiency. Our results provide a clear path to a cost-effective fabrication of QD conversion layer micro-LED displays over the full range of their applications.

AlGaN multiple quantum well deep‐ultraviolet micro‐light‐emitting diodes for high color conversion efficiency quantum dots display

“…The optically excited green QD film showed high color purity, which was due to the separate emission peak of the deep-UV Although the QDs showed high absorbance to deep-UV light, there were a few unconverted photons in this work, mainly due to the thin thickness of the color conversion layer. The residual pumping source could be further utilized to enhance the converted color intensity by optimizing the dimension of QD film 41 and other optical structures, 42 resulting in a negligible amount of UV residue. A cover filter would finally eliminate the UV light to ensure the display's safety for human eyes.…”

Technology and Applications of Micro-LEDs: Their Characteristics, Fabrication, Advancement, and Challenges

“…In 2021, Kuo's group proposed utilizing TiO 2 nanoparticles (NPs) as scatterers in QD ink 139 to improve the CCE by suppressing the reabsorption effect, as shown in Figure 18a. QD Photoresist.…”

“…In 2021, Kuo’s group proposed utilizing TiO 2 nanoparticles (NPs) as scatterers in QD ink to improve the CCE by suppressing the reabsorption effect, as shown in Figure a. They indicated that the PLQY decreased significantly with increasing film thickness or QD concentration, caused by increasing QD reabsorption because of QD agglomeration, as shown in Figure b–d.…”

An overview on the principle of inkjet printing technique and its application in micro-display for augmented/virtual realities

“…Still et al found that the addition of ionic surfactant sodium dodecyl sulfate (SDS) to the PS particles suspension led to a more uniform deposition after evaporation. A large number of SDS molecules accumulate at the interface of the contact line driven by capillary force, so that the surface tension of the edge of the droplet is reduced, and the difference in surface tension gradient causes the Marangoni flow toward the center of the droplet 138 .…”