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ALUMNI AND UIC COMMUNITY

Prof. Hyun Jae Kim’s research paper is published on Advanced Functional Materials

Concentration on theory and development history of solution-processed oxide thin film transistors (TFTs) for realizing flexible electronics

Prof. Hyun Jae Kim (School of Electrical and Electronic Engineering, Associate Dean of Academic Affairs in UIC) published a paper “A review of low-temperature solution-processed metal oxide thin-film transistors for flexible electronics” in world class multidisciplinary engineering journal “Advanced Functional Materials” (impact Factor 15.621, JCR top rank 3.38%). This research was guided by Prof. Hyun Jae Kim (contact author) and led by Ph. D. candidate students Jeong Woo Park and Byung Ha Kang (the first co-authors). This paper is a review of the solution-processed oxide thin film transistor (TFT) technology based on original and impactful research results and research conducted by Prof. Kim's research group over the past decade.

TFTs consist of many nanoscale thin-film layers and are essential electronic devices for liquid crystal display (LCD) and organic light emitting diode (OLED) display. Since TFTs are electronic devices that switch on and off the display screen (pixel), TFTs act as “brain” when a display is compared to a human. If the TFT exhibited high performance, it is possible to realize high quality, large area and transparent display. Recently, a TFT using an oxide semiconductor has been spotlighted as a next-generation material instead of an amorphous silicon (a-Si) based TFT. Products commercialized using oxide TFTs include Apple's iPad and LG's large OLED TVs. Additionally, oxide TFTs are also used in smart watches which have a limited size, such as Apple Watch. State-of-art techniques including rollable TVs and transparent displays exhibited by LG electronics are based on oxide TFTs. Likewise, oxide semiconductor is an important material that can be used for future displays.

Prof. Kim developed the world’s first solution-processed InGaZnO TFTs in 2009. Since then, his group has been conducting in-depth research into the development of solution-processed oxide TFTs and performance enhancement technologies that are easy to reduce fabrication cost, simplify the process, and control the composition (68 international journals published on this topic). This paper analyzes the academic research trend of low-temperature process, the biggest technical difficulty of solution-processed oxide TFTs, with statistical data. Over 350 solution-processed oxide TFT-related journals have been classified in terms of material, process, and structural engineering. Therefore, this paper has great significance in presenting recent issues and future research outlooks.

Figure 1. Approaches to low-temperature solution-processed oxide TFTs

Figure 2. A photograph of the transparent solution-processed oxide TFT fabricated by Prof. Kim’s lab at low temperature