The Polymer Society of Korea

배종석 (대구경북과학기술원)

최문기 (울산과학기술원)

양지웅 (대구경북과학기술원)

White light sources combining high efficiency, accurate color reproduction, and adjustable color temperature are key to advanced lighting and display systems. Conventional white LEDs based on blue chips with yellow phosphor coatings often suffer from limited color quality due to insufficient long-wavelength emission, while blended wavelength converters frequently experience efficiency degradation caused by inter-emitter energy transfer. Here, we present white LEDs employing vertically stacked quantum dot (QD) color-conversion films fabricated by transfer printing. Separating monochromatic QD layers into discrete stacked architectures effectively suppresses nonradiative energy exchange compared with mixed configurations. As a result, devices incorporating red, green, and yellow QD layers generate well-balanced white emission with near-ideal chromaticity and a high color rendering index. In addition, the correlated color temperature can be systematically tuned from approximately 4000 to 6000 K by adjusting the thickness of the yellow QD layer. This stacked QD conversion strategy offers an efficient and versatile route toward high-quality, tunable white LEDs.