Recent advances in flexible solution-processed thin-film transistors for wearable electronics

Solution-processed thin-film transistors (TFTs) are widely explored due to their high potential in flexible, cost-effective, large-area electronics, such as wearable electronics, sensor arrays, flexible displays, radio frequency identification antennas/tags, artificial skin, memories, and so on. This article aims to comprehensive study recent advancements in flexible solution-processed TFTs, focusing on their typical configurations, different active materials, biocompatible substrates, superior performance, and challenges, especially in the context of flexible wearable devices. The configurations of the flexible TFTs are classified into single-gate and double-gate topologies, which are discussed along with their related features and corresponding applications. In addition, the side-gate structure is included as an additional single-gate topology. Different types of flexible and biocompatible substrates (e.g., thin polymer films, papers, and textiles), solution-based semiconductors (e.g., organic, metal-oxide, carbon-based, and polysilicon semiconductors), gate dielectric (e.g., high-k binary and ternary oxides, multicomponent dielectrics, and polymer-based dielectrics), and conductors (e.g., metal-based and organic-based conductors) are reviewed in detail, highlighting their typical characteristics and latest publications. The methods used to assess the performance of flexible TFTs in terms of electrical and mechanical properties are illustrated with related examples. This paper provides an overview of the state-of-the-art flexible solution-processed TFTs for wearable electronics, highlighting the main challenges associated with their fabrication process and performance. Furthermore, it suggests a few of new possible research directions for solution-processed flexible TFT-based applications, which can benefit related researchers.