Transparent Active-Matrix Micro-LED Array Driven by Vertically Stacked TiO2/HfO2-Based Memristors

초록

Micro-light-emitting diodes (micro-LEDs) are highly promising for next-generation transparent displays owing to their exceptional brightness, fast response time, and environmental stability. However, conventional active-matrix (AM) driving schemes based on thin-film transistors (TFTs) and capacitors suffer from limited optical transmittance, scalability challenges, and complex fabrication. Here, a novel AM driving architecture is proposed, incorporating vertically stacked transparent memristor (T-MEMTs) to drive transparent micro-LEDs. The T-MEMT, composed of an ITO/TiO2/HfO2/ITO structure, exhibits 17 stable multilevel resistance states and excellent switching endurance, enabling precise brightness modulation without the need for external capacitors. Owing to its high optical transmittance (>85% in the visible range) and simple two-terminal configuration, the T-MEMT is monolithically integrated on top of micro-LEDs, significantly enhancing the integration density compared to TFT-based counterparts. To demonstrate the feasibility of the proposed AM scheme, an 8 x 8 transparent micro-LED array is fabricated via direct line deposition without transfer or bonding processes, successfully displaying static characters ("A", "S", and "L") and dynamic grayscale images by AM operation of T-MEMTs. This work offers a highly integrated, transparent, and scalable AM display platform suitable for applications in augmented/virtual reality, automotive head-up displays, and smart window technologies.

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