Carnegie Mellon University

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Jeong Ae Yoon

Flexible displays like flexible OLED, E-paper have received great interests due to their portabilities. They also company the innovative reduction of production costs; The substrates are usually transparent, flexible pastics like polyethylene, polyester, polycarbonate instead of glass substrate, one of the most expensive part of present displays. In addition, cheap and brief manufacturing process like roll printing, inkjet printing can be adopted instead of complicated photolithographic process. These flexible displays essentially require flexible field effect transistors(FETs). Organic FETs composed of only organic or organic-inorganic hybrid materials is the most desirable solution due to its mild processing condition, low manufacturing cost and so on.

Among the components of OFET, organic gate dielectrics also have investigated intensively. The key physical parameters of organic dielectrics are described in the equations below.



Dmax : the maximum possible electric displacement the gate insulator can sustain

k : the dielectric constant

EB : the dielectric breakdown field

Ci : the capacitance per area

d : insulator thickness


To increase charge mobility of OFET, k value is required to be high or d value to be low. Many materials which have high k value have studied as the gate dielectric layer. Polyvinyl phenol(PVP) or polyvinyl alcohol(PVA) films cured with melamine are representative examples of high k organic dielectrics. In the mean while, recent studies say the low k materials are superior in the stability of a device due to their little susceptibility of ionic impurities. The low k dielectrics are necessarily ultrathin to be compatible to gate dielectrics.


Therefore, our aim of study is to prepare ultrathin low k gate dielectrics by polymers of various structures. Furthermore, we are also investigating the property of devices fabricated with those gate dielectrics.


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Mellon Institute

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