Transfer-printed multi-stacked quantum dot color conversion layers for white light-emitting diodes

Abstract

White light-emitting diodes (LEDs) with high efficiency, high color rendering index (CRI), and a wide range of color temperatures are in high demand across diverse lighting and display applications. However, conventional methods, such as coating yellow phosphors onto blue LEDs, often result in low CRI due to insufficient red emission, while the use of mixed phosphors experience efficiency losses from interparticle energy transfer. Herein, we present multi-stacked quantum dot (QD) color conversion layers (CCLs) for white LEDs, fabricated via transfer printing. Our CCLs feature sequentially transfer-printed monochromatic QD layers in various colors, which effectively suppress interparticle energy transfer compared to mixed phosphor configurations. Systematic comparisons reveal that white LEDs with trichromatic QD CCLs achieve high-quality white light with balanced chromaticity (CIE coordinates of 0.33, 0.33) and CRI of 91, surpassing monochromatic and dichromatic CCL configurations. Furthermore, these trichromatic CCLs allow flexible tuning of the correlated color temperature (CCT) from warm white (4260 K) to cool white (6660 K) by adjusting the thickness of the yellow QD layer. Our transfer-printed QD CCLs represent an efficient and adaptable solution for next-generation white LED applications, advancing lighting and display technology toward highly efficient and customizable solutions.