Abstract

Foldable and rollable displays are of increasing interest recently. I will discuss the key technologies of TFTs for those applications. Non-laser detach technology was developed by using a CNTGO buffer layer inserted into PI substrate which helps easy detach and more self-standing plastic substrate [1]. We made oxide and LTPS TFTs on PI substrate using CNTGO buffer layer and investigated the effect of bending and rolling on the electrical properties of TFTs. Tensile stress is found to give more change to the TFT performance for both LTPS and oxide TFTs compared to compressive stress [2]. These results are related with out-folding or in-folding of  smartphone displays. The split of both source/drain and semiconductor layer is important for more flexible TFTs [3]. The device performance is also improved a lot by splitting for etch-stopper oxide TFT [4]. The TFT in neutral plane is also very robust under bending [5]. I will discuss one directional stretchable TFT array for high resolution biosensors and thin-film encapsulation of top-emission OLED using SiNx/polymer multilayer for highly foldable OLED.