  Colloidal quantum dots are promising next-generation phosphors to enhance the
color rendition of light-emitting devices (LEDs) while minimizing the
brightness drop. In order to exploit the beneficial tunability of quantum dots
for highly efficient devices, optimization and determination of the performance
limit are of crucial importance. In this work, a facile preparation process of
red-emission quantum dot films and simulation algorithm for fitting this film
with two commercial LED flat lamps to the optimized performance are developed.
Based on the algorithm, one lamp improves from cold-white light (8669 K) with
poor color rendition ($R_{a}=72$) and luminous efficacy (85 lm/W) to warm-white
light (2867 K) with $R_{a}=90.8$ and $R_{9}=74.9$, and the other reaches
$R_{a}=93\sim95$. Impressively, the brightness drop is only about $15\sim20\%$.
Furthermore, our device shows reliability over 1000 hours with only PET
(polyethylene-terephthalate) films as the barrier, indicating that this
auxiliary red-emission film can be easily applied to improve the color
rendition of most commercial LED flat lamps.
