Fabrication Process of MicroLED Film for Achieving Vertical Current Injection Using Transfer Technology

Flexible light‐emitting devices have attracted attention as a novel bio‐interface connecting living tissues with electronics due to their high brightness, low power consumption, and durability in humid environments. Introduction of vertically current‐injected micro‐light‐emitting diodes (MicroLEDs) into this film can enhance the MicroLED effective area and improve device characteristics. In this study, the MicroLED transfer technology onto conductive materials is investigated. The feasibility of batch transferring MicroLEDs onto a conductive polymer is demonstrated by PEDOT:PSS layer. For non‐Ohmic characteristics between n‐GaN and PEDOT:PSS, a backside‐open MicroLED hollow structure is proposed, enabling the formation of Ti/Au electrodes on the backside of MicroLED. By transferring the fabricated vertically current‐injected MicroLEDs onto the PEDOT:PSS layer, a flexible vertically current‐injected LED film is achieved, observing uniform blue light emission. The developed MicroLED film holds promise as a new neuroscience tool for targeting specific areas of the brain with light.