Spectrum Continuously Tunable White LED Based on Bilayer Thickness-Graded Quantum Dots

Regulating the emission spectrum of white light-emitting diode (WLED) is crucial for enhancing lighting quality and advancing smart lighting technology. This study proposes a device to achieve continuous tunability of the multicolor emission spectrum by designing a bilayer cadmium selenide (CdSe)-based quantum-dot (QD) light-conversion structure and the corresponding illuminating control system. Spectral modulation is achieved by a three-pronged approach: 1) the fabrication of the thickness-graded QD film; 2) preassembly monochromatic spectra characterization and spectral optimization; and 3) postassembly mechanical control of a push rod connected to the blue LED chip. Compared to others, the proposed approach provides precise control over continuous spectra modulation in both simulation and experimental settings using just two parameters: driving voltage and blue LED chip position. This device offers a wide range of options for correlated color temperature (CCT) ranging from approximately 2000–60 000 K and illuminance from approximately 0–200 lx. Furthermore, the detailed study of light modulation offers viable approaches for realizing tunable WLEDs in smart lighting and Internet of Things (IoT) systems.