  Light-emitting diodes (LEDs) are efficient light sources extensively applied
in people's daily life nowadays, with profound effect on their psychological
and physiological state subtly and deeply. The correlated color temperature
(CCT) the eyes perceive is a key parameter, but the CCT tuning technology of
LEDs remains in the development stage. In this study, an electrochromic (EC)
material is employed in the tuning device, exhibiting a wide CCT tuning range
from 3,200 K to 6,900 K, varying almost along the black-body locus. The driving
voltage is lower than 2.4 V, with luminosity loss less than 16%. Using the EC
materials, the performance of CCT tuning technology is able to be further
enhanced.
