The quantum dot (QD) color-conversion efficiency (CCE) in GaN micro-light-emitting diodes ( μLEDs) is greatly improved by non-radiative energy transfer (NRET) mechanism. An array of deep nano-holes with a diameter of about 1 μm was fabricated in μLED mesas ( 40×60 μm ² ) by nanoimprint lithography. The nano-holes were etched straight through the μLED active region to ensure that the filled QDs were in extremely close contact with the active region. The absorption efficiency and emission efficiency of QDs are effectively improved by NRET, resulting in a superhigh CCE in QD- μLED hybrid devices. Compared to μLED devices with conventional spin-coated QDs, the CCE of novel nano-hole μLEDs with filled QDs has been enhanced by about 118%.

A localized surface plasmon (LSP) coupling nanorod μLED using graphene as a transparent conductive electrode structure was demonstrated. The optical performance of the μLED with LSP coupling is enhanced by about 36% in external quantum efficiency and 84% in photoluminescence measurements as compared with the LSP-free sample. This LSP coupling enhancement relies on the very large sidewall area provided by the nanorod structure and the zero distance contact between the nanoparticles and nanorods. This work provides a broad prospect for the application of LSP in the μLED field.

Realizing full color GaN-based micro- and nano-light-emitting diode (nLED) displays with quantum dots (QDs) being the color conversion media remains challenging because of the limited QD color conversion efficiency (CCE). In this article, by using GaN-based nanorod LED as the light source and exciting the QDs by nonradiative energy transfer (NRET) method, a nanorod LED with ultrahigh CCE has been realized. At the same time, a single electrical contact alternating current (ac)-driven electroluminescence (EL) method is adopted to investigate the relationship between frequency and nLED performance. Different from the double terminal injection mode, on the premise of lighting up the nanorod LED, the ac-driven can also avoid the necessity of external p-type and n-type electrodes, thus simplified the manufacturing process of LED. The final optical measurement shows that the CCE of this hybrid color conversion nLED driven by single contact electrode can reach up to 86.67% under the ac voltage of 60 V and an ac frequency of 14.2 MHz, which shows that the energy utilization efficiency can be effectively improved by NRET.

Micro-light-emitting diodes (μLEDs), with their advantages of high response speed, long lifespan, high brightness, and reliability, are widely regarded as the core of next-generation display technology. However, due to issues such as high manufacturing costs and low external quantum efficiency (EQE), μLEDs have not yet been truly commercialized. Additionally, the color conversion efficiency (CCE) of quantum dot (QD)-μLEDs is also a major obstacle to its practical application in the display industry. In this review, we systematically summarize the recent applications of nanomaterials and nanostructures in μLEDs and discuss the practical effects of these methods on enhancing the luminous efficiency of μLEDs and the color conversion efficiency of QD-μLEDs. Finally, the challenges and future prospects for the commercialization of μLEDs are proposed.

To enhance the emission of GaN-based Micro-LEDs (μLEDs), we etched uniform nanorods (NRs) on the μLED surface and filled the nanorod gaps with spin-on glass (SOG) containing mixed Ag nanoparticles (NPs). The nanorod structure creates a conducive environment for close interaction between Ag NPs and quantum wells (QWs), facilitating the coupling of Ag NPs as localized surface plasmons (LSPs) with the QWs to enhance light emission. The SOG acts as an insulating layer between Ag NPs and NRs, preventing electron leakage, while also serving as a planarization material for the nanorod structure. This configuration allows for the fabrication of a planar Indium Tin Oxide layer without short-circuiting the nanorod structure. Compared to traditional planar Micro-LEDs, NR-μLEDs with SOG-encased Ag NPs exhibit a 50% increase in electroluminescence (EL) intensity and a 56% increase in photoluminescence (PL) intensity. This work paves the way for broader applications of LSP in μLEDs.