High-performance metal oxide TFTs for flexible displays: materials, fabrication, architecture, and applications

Flexible display technology is actively explored as a cornerstone of the next generation of wearables and soft electronics, set to revolutionize devices with its potential for lightweight, thin, and mechanically flexible features. Flexible thin-film transistors (TFTs) utilizing promising materials such as amorphous silicon (a-Si), low-temperature polysilicon (LTPS), metal oxides (MOs), and organic semiconductors are essential to enable flexible platforms. Among these, MO semiconductors stand out for flexible displays due to their high carrier mobility, low processing temperature requirements, excellent electrical uniformity, transparency to visible light, and cost-effectiveness. Furthermore, the maturity of MO TFT technology in the existing display industry and its compatibility with complementary-metal-oxide-semiconductor (CMOS) processes are driving active research toward integrated circuits for wearable electronics beyond display applications. Specifically, achieving both high mechanical flexibility and electrical performance in MO TFTs is crucial for implementing complex integrated circuits such as microprocessors and backplanes for ultra-high resolution augmented reality (AR)/virtual reality (VR) displays. Therefore, this review provides recent advances in high-mobility flexible MO TFTs, focusing on materials, fabrication processes, and device architecture engineering methods for implementing MO TFTs on flexible substrates, as well as strategies to reduce the impact of mechanical stress on MO TFTs. Next, MO TFT-based display and integrated circuit applications for next-generation flexible and stretchable electronics are introduced and discussed. Finally, the review concludes with an outlook on the potential achievements and prospects of MO TFTs in the development of next-generation flexible display technologies.