It is nearly impossible to integrate RGB micro LEDs on a single wafer due to material incompatibility. This paper solves the manufacturing issue by using a blue or UV micro LED array below a Quantum Dot Color Conversion Layer (QDCCL). A PDMS mold with micro channels is filled with the red and green QD which get excited by the blue led array. This enables a pixel size of 200 200 µm and sub pixel size of 140 x 50 µm. The quantum yield of the red and green QDs were 51% and 90% with a color gamut of 131% NTSC coverage. The resulting method was easy to fabricate, low cost, and high performance.
This paper compares traditional inkjet and photolithography methods to the new microfluidic approach.
Source: Microfluidics-based quantum dot color conversion layers for full-color micro-LED display
