Abstract
Subwavelength-scale nanorods were implemented on the hexagonal pyramid of photochemically etched light-emitting diodes (LEDs) to improve light extraction efficiency (LEE). Sequential processes of Ag deposition and inductively coupled plasma etching successfully produce nanorods on both locally unetched flat surface and sidewall of hexagonal pyramids. The subwavelength-scale structures on flat surface offer gradually changed refractive index, and the structures on side wall of hexagonal pyramid reduce backward reflection, thereby enhancing further enhancement of the light extraction efficiency. Consequently, the nanorods implemented LED shows a remarkable enhancement in the light output power by 14% compared with that of the photochemically etched LEDs which is known to exhibit the highest light output power. Theoretical calculations using a rigorous coupled wave analysis method reveal that the subwavelength-scale nanorods are very effective in the elimination of TIR as well as backward reflections, thereby further enhancing LEE of the LEDs.
Highlights
Subwavelength-scale nanorods were implemented on the hexagonal pyramid of photochemically etched light-emitting diodes (LEDs) to improve light extraction efficiency (LEE)
Internal quantum efficiency (IQE) of the LEDs has been achieved to nearly 80%6,7, much room remains for enhancement of the light extraction efficiency (LEE), so that they can serve as next-generation light sources
The subwavelength-scale nanorods implemented on the pyramids structures (Fig. 1b) could effectively enhance LEE by reducing total internal reflection (TIR) at the flat zone as well as by eliminating the backward reflection at the side wall of the hexagonal pyramids
Summary
Subwavelength-scale nanorods were implemented on the hexagonal pyramid of photochemically etched light-emitting diodes (LEDs) to improve light extraction efficiency (LEE). The subwavelength-scale structures on flat surface offer gradually changed refractive index, and the structures on side wall of hexagonal pyramid reduce backward reflection, thereby enhancing further enhancement of the light extraction efficiency. The sidewall angle of 31.6° was known not to be an optimal sidewall angle for the light extraction[9] because 50% of incident light was reflected at the side wall of hexagonal pyramid (Fig. S1b,c) Such problems can be solved by employing subwavelength-scale nanorods on both the flat surface region and the side walls of hexagonal pyramid. The formation of subwavelength-scale structures on the flat surface could offer a gradually reducing refractive index to air, and the subwavelength-scale structures on side walls of hexagonal pyramid could decrease he backward reflection, thereby enhancing further enhancement of the LEE
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
