# High-Performance Color-Converted Full-Color Micro-LED Arrays
## 1 Introduction  
The micro-LED display is a technology that has expanded rapidly in recent years because of its outstanding features such as low power consumption, quick response, long lifetime, and wide color gamut [1; 2; 3; 4]. However, the fabrication of full-color micro-LED arrays is still under the process of channeling. The most commonly used routes to fabricate these devices involve epitaxial growth of red, green, and blue (RGB) active materials on different substrates followed by chip fabrication, wafer dicing, and pick-and-place robotic manipulation into individually packaged components for interconnection by bulk wire bonding. However, dicing becomes more difficult as the chip size decreases beyond 100 \(\upmu\)m \(\times\) 100 \(\upmu\)m, and integrating them on the same thin-film transistor-based glass substrates through mass transfer, which requires precise alignment for each pixel, becomes a challenge [5; 6; 7]. Moreover, the light-emission efficiencies and degradation rates of RGB micro LEDs are different; as a result, a complicated driving circuit may be needed to maintain the color-rendering index during operation.  
A simpler method to achieve full color without mass transfer of individual R, G, B chips is to utilize the color filters to achieve RGB subpixels while generating white light by deposition of a yellow color converter on blue micro-LEDs [5; 6]. In this device configuration, the color downconversion layer does not need to be pixilated; thereby it becomes more feasible for manufacturing. However, the color filters would absorb two-thirds of the outgoing light. In addition, color crosstalk would occur, owing to scattering of the color-conversion layer.  
Another approach to avoid the mass-transfer process is the fabrication of full-color micro LEDs based on blue or UV micro LEDs and color-conversion materials of blues, greens, and reds. For color-conversion materials, nanophosphors and quantum dots (QDs) can be used [8; 9; 10; 11]. For example,Han et al. [9] deposited RGB QDs on top of a UV LED array using the aerosol jet printing method to form individual subpixels. This configuration is advantageous in that it does not require a color filter and offers a possibility of achieving high efficiency and a wide color gamut. However, a thick layer of QDs with high optical density is required for high color downconversion efficiency. In addition, longer processing times and special equipment are required.  
So, there is a need for a method that can deposit a large amount of color-conversion materials on blue pixels in a single process with precise alignment for each pixel. Photolithography is a useful method to achieve this purpose. However, there is no report on the fabrication of a micro-sized color-conversion layer based on photolithography. In this paper, we propose an efficient technique to fabricate full-color micro-LED pixels using the mixture of photocurable acrylic and nano-organic color-conversion materials by conventional lithography technique. We can significantly control the position, size, and thickness of the color-conversion layers to fabricate full-color micro LEDs. This study attempts to provide a solution for fabricating full-color micro-LED displays.