Pentacene-based organic superlattice transistors (OSLFETs) using the monolayer (ML) thickness of organic pentacene
and amorphous organic material have been studied. By changing the unit number of pentacene (2 ML) and amorphous
organic layers, transistor characteristics, namely, mobility, threshold voltage and on-off ratio, were markedly changed.
Under optimum stacked layer conditions, the mobility was determined to be 1.35 cm<sup>2</sup>/Vs, and the on-off ratio, 10<sup>6</sup>. By
changing the unit number of pentacene and amorphous organic layers, the sheet charge was determined to be 6.2×10<sup>11</sup>
cm<sup>-2</sup>. This superlattice configuration concept is expected to improve carrier transport and control the threshold voltage
for an integrated circuit configuration.
We propose an oscillation method of solution-processed organic film coating. This method hindered a flow of solvent
with organic materials during drying process. We have applied this technique into fabrication of OLEDs. In this time,
oscillation is induced using piezoelectric actuator and wetted plastic roller is used for coating the organic film. By doing
this method, uniform organic film with a mean roughness of 3.8 nm was achieved. Spin-coated poly(ethylene
dioxythiophene) /poly(styrene sulfonate) (PEDOT) was used for hole buffer layer. Polyvinylcarbazole (PVCz) as a hole
transport material, (BND) as an electron transport material, and coumarin 6 (C6) as an emission material were used.
Device structure of ITO /PEDOT (40 nm)/PVCz+BND+C6 (100 nm)/LiF (1 nm)/ Al with area of 30×30 mm<sup>2</sup> were tested. Emission was dramatically improved by changing the oscillation condition and uniform emission was observed at higher frequencies. This technique will be promising for large-area production and short tact time. And this method is also applicable for other fabrication methods, such as, spray method and ink-jet printing method.