RGB Arrays for Micro-Light-Emitting Diode Applications Using Nanoporous GaN Embedded with Quantum Dots

Abstract

The multiple light scattering of nanoporous (NP) GaN was systematically studied and applied to the color downconversion for micro-light-emitting diode (LED) display applications. The transport mean free path (TMFP) in NP GaN is 660 nm at 450 nm (light wavelength), and it decreases with a decreasing wavelength. It was observed that the short TMFP of the NP GaN increased the light extinction coefficient at 370 nm by 11 times. Colloidal QDs were loaded into a half 4″ wafer scale NP GaN, and 96 and 100% of light conversion efficiencies for green and red were achieved, respectively. By loading green and red QDs selectively into NP GaN mesas, we demonstrated the RGB microarrays based on the blue-violet pumping light with green and red color converting regions.

High-Uniform and High-Efficient Color Conversion Nanoporous GaN-Based Micro-LED Display with Embedded Quantum Dots

“…Colloidal quantum dots (QDs) have been shown to have a higher quantum yield (QY), a narrower emission linewidth, and a shorter luminous lifetime [17]. As a result, recent demonstrations of QD-based RGB micro-LED arrays have identified them as promising color conversion materials [18,19]. The passivation of the surface of QD films using polymers is a well-known approach for lowering the density of surface trap states, preventing non-radiative recombination, and thereby increasing the QD's QY [20].…”

“…Lightscattering media have recently been employed in energy harvesting devices such as solar and photo electrochemical cells to enhance light absorption [29][30][31]. Light undergoes multiple scattering and diffusive transport as the scattering strength and medium thickness increase [32], leading to increased optical path length and enhanced light absorption [18]. A combination of the scattering medium and GaN-based LEDs is extremely desirable, due to the commercialization and development of highly efficient GaN-based blue LEDs, as well as GaNs' low light absorption in the visible spectrum [33].…”

Full-Color Realization of Micro-LED Displays

“…In 2020, Kang et al applied a nanoporous (NP) GaN structure to the QD color conversion of a micro-LED display [85,86]. Compared to ordinary QD films, the GaN NP structure has high structural stability and improves the light absorption rate of QD through its unique type of multiple light scattering.…”

“…Reproduced from[84], with permission from John Wiley and Sons, 2019; (c) GaN nanoporous (NP) structure conversion layer preparation process. Reprinted with permission from[85]. Copyright (2020) American Chemical Society.…”

61‐3: Investigation of AlGaN‐Based Deep‐UV MicroLED as Highly Efficient Excitation Source for Green Perovskite Quantum‐Dot Display

“…Blue Micro-LED as the pumping source with red and green quantum dots was widely researched, the low efficiency for pumping green quantum dots and the color mixing become the main problem [6][7]. As the different types of quantum dots show higher absorption efficiency to lower wavelength photons, blueviolet and near-UV Micro-LED were proposed to diminish the color rendering and increase the excitation efficiency [8][9]. While the research on AlGaN-based Deep-UV Micro-LED is still challenging, few efforts are invested in its application of excitation source of R/G/B quantum dots.…”