Fig. 1. The corresponding developments of QD micro-LED. (a) The methods of mass production. (b) Atomic layer deposition passivation. (c) The mechanism of energy transfer between micro-LED chip and QDs. (d) Structural design for QD micro-LEDs. Figures reproduced with permission from: (a) ref.¹⁴, Royal Society of Chemistry; ref.¹⁵, under a Creative Commons Attribution License; ref.²², Chinese Laser Press; (d) ref.²⁸, Optical Society of America; ref.²⁹, John Wiley and Sons; ref.³⁰, under a Creative Commons Attribution License.

Fig. 2. Optical properties of the hybrid QW/QDs. Figure reproduced with permission from ref.³⁵, Springer Nature.

Fig. 3. (a) Electroluminescence (EL) wavelength spectrum of a 100 μm × 100 μm AlGaInP micro-LED and (b) light output power characteristics of 100 μm × 100 μm and 20 μm × 20 μm micro-LEDs with different sidewall treatments. The insets in (a) are EL images of the five micro-LED sizes at 1 A/cm². Figures reproduced with permission from ref.⁴⁵, Optical Society of America.

Fig. 4. (a) PL emission spectra of micro-LEDs with and without ALD passivation. (b) Temperature-dependent time-resolved photoluminescence decay curves of micro-LEDs with and without ALD. Figures reproduced with permission from ref.⁴⁶, under a Creative Commons Attribution License.

Fig. 5. (a) Schematic of the nano-pillar LED. (b) Cross-sectional SEM image of a nano-pillar LED device. (c) SEM image of the QD-coated nanopillars. Figures reproduced with permission from ref.²⁸, Optical Society of America.

Fig. 6. Electroluminescence spectra of the (a) nano-pillar LED and (b) planar control samples with and without QD coupling. (c) Time-resolved photoluminescence decay curves of a nano-pillar LED sample with and without QD-coating. Figures reproduced with permission from ref.²⁸, Optical Society of America.

Fig. 7. (a) Schematic representation, (b) cross-sectional, and (c) top SEM images of a photonic quasicrystal LED hybridized with QD color converters. Figures reproduced with permission from ref.⁵⁰, under a Creative Commons Attribution License.

Fig. 8. Electroluminescence spectra of a PQC LED before (black solid line) and after hybridization (red solid line) with (a) QD-585 and (b) a blend of QD-535, QD-585, and QD-630, along with the absorption spectrum of QD-585 (orange dashed line) in (a) and the absorption spectrum of QD-535 (green dashed line), QD-585 (orange dashed line), and QD-630 (red dashed line) in (b). (c, d) Effective quantum yield (red solid circles) and effective color conversion efficiency (black open squares) of a PQC LED hybridized with QD-585 in (c) and with the QD blend in (d). Figures reproduced with permission from ref.⁵⁰, under a Creative Commons Attribution License.

Fig. 9. (a) Schematic diagrams of hybrid h-LED. (b) Bird’s eye view SEM image of ordered nano-hole arrays in the absence of QDs with ITO current spreading layer on the surface. (c) Cross-sectional view SEM image of nano-holes filled with NCs, and (d) transmission electron microscopy (TEM) image of CdSe/ZnS core/shell QDs and a high-resolution image in the inset. Figures reproduced with permission from ref.⁵¹, John Wiley and Sons.

Fig. 10. The physical schematic diagram of an NRET process. Figures reproduced with permission from ref.⁵¹, John Wiley and Sons.

Fig. 11. (a) Epitaxial wafer. (b) Three subpixels of a green micro-LED, a blue micro-LED, and a QD-micro-LED. (c) Deposition of transparent conducting oxide (TCO) film and P/N electrodes. (d) Covering distributed Bragg reflector (DBR) filter. (e) Full-color display panel composed of the proposed hybrid QD-micro-LED. (f) Cross-sectional view of a single RGB pixel. Figures reproduced with permission from ref.⁴⁶, Chinese Laser Press.

Fig. 12. (a) SEM image of RGB pixel array. (b) SEM image of QD-micro-LED with 30° tilt angle. (c) TEM image of the contact area between multi-QWs and QDs. (d) TEM image of 1 nm Al₂O₃ deposited on the sidewall of an QD-micro-LED through ALD. Figures reproduced with permission from ref.⁴⁶, Chinese Laser Press.

Fig. 13. (a) Absorption spectrum of red QD and EL spectrum of blue nano-ring micro-LED. (b) TRPL curves of nano-ring micro-LED with and without red QDs. (c) Normalized EL spectra of RGB hybrid full-color micro-LED devices. (d) Color gamut of RGB hybrid full-color micro-LED device, NTSC, and Rec. 2020. Figures reproduced with permission from ref.⁴⁶, Chinese Laser Press.

Table 1. Luminous performance of LED device based mainly radiative energy transfer or NRET.