|Professor Choi Byoung-deog (kyosu.net)|
Recently, problems of image sticking of flexible displays have been rising. In response, Professor Choi Byoungdoeg’s research team, from the School of Electronic Electrical Engineering, analyzed the cause of the problem through joint research with Samsung Displays. According to the research, the charging effect of polyimides, which are used as substrates of flexible displays, influences the transistor, further leading to image sticking on the flexible displays. To be specific, polyimides endure at a different range of temperatures and have a small coefficient of expansion and high heat resistance. When polyimides go through a coating procedure with a heat-curing process, the curing temperature increases, causing an increase in the charging effect of polyimides. This increase provokes abnormal movements of the transistor’s working voltage, which finally triggers the afterimage on the flexible display. In addition, with polyimides’ curing temperature increase, the reduction of the resistance rate allows fluorine ions to be accumulated on polyimides when there is external stress; this provokes an increase in the charging effect. Prof. Choi said that “This study has presented a direct correlation between polyimides’ curing temperatures and image sticking on flexible displays, and it is expected to play a crucial role in improving the reliability of all flexible devices using polyimide substrate.” This research was published on November 8th in an online peer-reviewed open access scientific mega journal, Scientific Reports.
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