New Material Offers Faster and Higher Resolution Displays

A novel material is being developed to enable quicker and improved resolution in displays. Scientists from Hokkaido University describe what makes this material so unique, paving the way for its application and further development.

New Material Offers Faster and Higher Resolution Displays

Image Credit: Olexandr Taranukhin/

All displays are composed of a lattice of small bits of light called pixels, the brightness of which may be changed individually. The total number of pixels—and hence the resolution and display size—are restricted by the number of pixels that can be addressed in a fraction of a second.

As a result, display manufacturers attempt to utilize materials in the pixel control units that have a very high “electron mobility,” which is an indicator of how rapidly current will begin to flow through such a control unit in response to a voltage being applied—and therefore how “quick” the pixel is.

A new material known as “ITZO” (for the elements indium, tin, zinc, and oxygen) claims to be up to seven times quicker than the existing robust material. However, it is unclear where this improvement originates from, which limits its use in industrial applications.

Hiromichi Ohta, a material scientist at Hokkaido University, and his colleagues clarified this fact using their unique measurement method. They demonstrated that the increased electron mobility ultimately resulted from the strange fact that in ITZO films of sufficient thickness, free charges collect at the interface with the carrier material, allowing passing-through electrons to travel unchecked through the bulk of the material.

The study was published in the journal Applied Electronic Materials.

The unique ability of the group is based on a simple formula: electron mobility is proportionate to the free travel time of the charge carriers—electrons—divided by their effective mass. It is also challenging to determine what factor is responsible for electron mobility since effective mass and free travel time cannot be determined with the same ease as the electron mobility itself.

However, Ohta’s team determined the effective mass of the electrons and the free travel time by observing how the electric field within the material alters in response to an applied magnetic field and a temperature gradient.

It turns out that the free trip time is substantially higher and the effective mass is considerably lower than in existing state-of-the-art materials, and that both of these variables together lead to increased electron mobility. They might also determine how the interface and bulk of the material affect these effects by watching how their results vary with ITZO material thickness.

Using the knowledge we gained from this study, we may in the future design other transparent oxide semiconductor thin-film transistors with different chemical compositions that exhibit even better electron mobility properties.

Hiromichi Ohta, Material Scientist, Hokkaido University

The current research is a breakthrough for the next generation of ultra high-resolution displays.

This study was funded by the China Scholarship Council (202107090085), Grants-in-Aid of the JSPS (22K14303, 19H05788, 22H00253), the Start-Up Fund of Jiangsu University (5501310015), the Guangdong Basic and Applied Basic Research Foundation (2021A1515110881), and the Youth Fund of Foshan (Southern China) Institute for New Materials (2021AYF25009).

Journal Reference:

Yang, H., et al. (2022) Thermopower Modulation Analyses of High-Mobility Transparent Amorphous Oxide Semiconductor Thin-Film Transistors. Applied Electronic Materials.


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