Oxide semiconductors and hybrid materials for sustainable flexible electronics

Abstract

The transition to Society 5.0 emphasizes enhanced connectivity between people and the digital space and underscores the increased significance of information including its accessibility. Thin-film transistors (TFTs) play a pivotal role in displays, sensors, and edge devices, which are fundamental components of the modern information infrastructure. Recently, amorphous oxide semiconductors (AOS) have gained prominence as exceptional TFT materials, due to their remarkable blend of electrical performance, transparency, and energy efficiency. Nevertheless, AOS TFTs are primarily fabricated via vacuum process. As Society 5.0 takes shape, a surge in ubiquitous devices is anticipated, necessitating cost-effective high throughput fabrication methods. Thus, a paradigm shift towards solution process will be needed since solution process implies that TFT layers can be produced with: (1) cost-effective equipment, (2) up to 99% material utilization, and (3) a low temperature process which is needed for applications in healthcare, energy, and electronic devices. Although improvements in the performance of solution AOS TFTs have been reported, further work is needed for it to be comparable with vacuum process.
Truly achieving high throughput and cost-effective fabrication also requires that all TFT layers are solution processed. Early variations of fully solution-processed TFTs were challenging to fabricate, had insufficient performance (mobility (μ) < 1 cm²/Vs), and poor reliability. Therefore, high temperature (>400°C) process and exotic materials were needed to obtain μ < 10 cm²/Vs. Here, we demonstrate how employing solution processed hybrid materials and low temperature processing of AOS through photonic process (UV, laser) and plasma process can be leveraged to develop fully solution processed TFTs with high performance (μ > 30 cm²/Vs) and improved stability. We will also show how Machine Learning methods can be used as a cost-effective method to augment experimental methods in predicting electrical properties of AOS. Furthermore, methods to inhibit impurities in precursors will be presented as well as novel device architectures that minimizes the influence of channel defects on TFT carrier transport.