A review of multi-stacked active-layer structures for solution-processed oxide semiconductor thin-film transistors

In this review, the multi-stacked active-layer (MSAL) structures for the solution-processed amorphous oxide semiconductor (AOS) thin-film transistors (TFTs) are summarized to improve their electrical characteristics and stabilities based on the authors' previous researches. The MSAL structures can overcome an inherent weakness of the solution-processed AOS TFTs, which is the creation of porosities from solvent volatilization. Furthermore, by modifying each layer, the performance and reliability of the solution-processed AOS TFTs could be improved more. Here, the fundamental studies of MSAL structures with homo-stacked active-layer TFTs are presented, and the various modulations of active layers in hetero-stacked active-layer TFTs are covered. In addition, the effect of the interface between the stacked layers is also discussed.