Combinatorial Patterning of Red- and Green-Emitting Core–Shell Cd(Se,S)/(Cd,Zn)S Quantum Nanoplatelets for High-Resolution Color-Converter Microdisplays

Achieving high-resolution and cost-effective microdisplays for augmented and virtual reality applications now requires shaping the color conversion quantum-dot-based layers into structures corresponding to micropixels. We propose herein an alternative and versatile approach for addressing this challenge, nanoxerography, an electrostatic-based technique to selectively direct the assembly of colloidal nano-objects on precisely chosen areas of electrets. Coassembly of red- and green-emitting core–shell Cd(Se,S)/(Cd,Zn)S quantum nanoplatelets was performed on passive (PMMA/ITO/glass) and active (PMMA/ITO/GaN μLEDS) substrates. Topographical, optical, and electro-optical characterizations were further realized. Lateral resolution for subpixels of 800 nm (using charge injection by atomic force microscopy) and 3 μm (using charge injection by electrical microcontact printing) over surfaces larger than 1 cm2 in the later case was demonstrated. Nanoxerography was also proven to not alter the optical properties of the assembled quantum nanoplatelets. Without even the need of optical black barriers, no crosstalk between quantum nanoplatelet-based subpixels was observed for interspace greater than 1 μm. Red emitting quantum nanoplatelets assembled as 7.5 μm squared subpixels on active GaN blue-lit active substrates give an external quantum efficiency and internal quantum efficiency of 7.5 and 17%, respectively.