Dielectrophoretic-assisted trapped-assembly for fin-LED display

We propose a high-precision assembly technique for realizing high-resolution nano-to microscale displays using a trapped-assembly approach that integrates a doctor-blade-based ink-delivery system with dielectrophoresis (DEP)-induced assembly.Octadecyltrichlorosilane (OTS) self-assembled monolayers (SAMs) were coated onto the pixel-defined layer (PDL) to promote ink trapping and confine fin-LEDs within individual pixels during assembly.Key process parameters-including the viscosity and dielectric properties of the ink solvent, speed and number of blade passes, blade-to-substrate gap, and applied DEP voltage and frequencywere systematically optimised, as these parameters affect solvent confinement of the solvent and fin-LED assembly behavior.Under optimised conditions, achieved through precise control of solvent polarity, DEP force and torque, and doctor-blading parameters, all 400 pixels were successfully assembled.Statistical analysis revealed that 90% of the pixels contained 12-20 fin-LEDs, with an average of 16.3 fin-LEDs per pixel and a standard deviation of 3.5.The overlap ratio was limited to 8%, and 92% of the fin-LEDs were accurately assembled, of which 95% established contact with the p-GaN surface.Electroluminescent devices fabricated using the assembled fin-LEDs exhibited bright and uniform emission across the entire pixel array, confirming their excellent assembly quality and high electrical reliability.The DEP-based trapped-assembly method provides a reliable and scalable strategy for the practical integration of nano-to microscale LEDs in next-generation high-resolution display technologies.