Vertically stacked RGB LEDs with optimized distributed Bragg reflectors.

Area of Science:

• Optoelectronics
• Materials Science
• Photonics

Background:

• Vertically stacked red-green-blue (RGB) light-emitting diodes (LEDs) are crucial for white light generation.
• Improving luminous efficiency in RGB LEDs is an ongoing challenge.
• Existing structures may suffer from inefficient light management.

Purpose of the Study:

• To design and fabricate novel wavelength-selective distributed Bragg reflectors (DBRs) for vertically stacked RGB LEDs.
• To optimize DBRs for selective reflectance in the RGB spectral region.
• To enhance the luminous efficiency of white light emission from RGB LEDs.

Main Methods:

• Theoretical calculations and simulation modeling were used to optimize DBR structures.
• Fabrication of vertically stacked RGB LEDs incorporating the optimized DBRs.
• Optical performance characterization of devices with and without DBRs.

Main Results:

• Optimized DBRs achieved selective reflectance in the RGB spectral region.
• DBRs effectively reflected downward emission without filtering lower chip emissions.
• Luminous efficiency for white emission (3000-8000 K) increased by 1.6-7.4%.

Conclusions:

• The proposed wavelength-selective DBR structure is effective in enhancing RGB LED performance.
• This innovation offers a viable method for improving white light efficiency in stacked LEDs.
• The study validates the optical performance improvements through experimental verification.