The effect of the reflective property of a reflection film on the performance of backlight units with quantum-dot films for LCD applications

The luminance and color properties of backlight units with quantum-dot (QD) films were investigated through experimentation and optical simulation. Red and green QD films were arranged in four different configurations above and below the light guide plate (LGP). The on-axis luminance of the backlight units with QD films was much larger when diffuse reflectors were used instead of specular reflectors, irrespective of the QD configuration. This result is attributed to the higher color conversion efficiency and the outcoupling efficiency caused by the spreading of the light reflected from the diffuse reflectors. The ‘red QD film-LGP-green QD film’ combination exhibited the highest luminance performance among the four configurations, which can be explained in terms of the reduced radiation load on the two QD films, besides the nearly zero absorption of the red light emitted from the red QD film by the green QD film. The simulation results reproduced all these main results, which indicates that optical simulation can be a useful tool for the optimization of the optical structure of backlight units with QD films in advance of experiment and fabrication.