Articles you may be interested inAll-organic thin-film transistors made of poly(3-butylthiophene) semiconducting and various polymeric insulating layers

Articles you may be interested inThree-dimensional organic field-effect transistors: Charge accumulation in the vertical semiconductor channels Appl. Phys. Lett. 93, 173301 (2008); 10.1063/1.3007984 Time-of-flight mobility measurements in organic field-effect transistors J. Appl. Phys.Effects of metal penetration into organic semiconductors on the electrical properties of organic thin film transistors Appl.

We have fabricated fully patterned all-organic thin-film transistors with a variety of organic polymer insulators. Poly(3-butylthiophene) deposited by spin coating was used as the active organic layer. We have built top-gate structures with gates printed on top of the gate dielectric layer. The field enhanced current is weak with poly(4-vinyl phenol), but much stronger with polyvinyl alcohol and cyanoethylpullulan. Carrier mobilities as large as 0.04 cm2/V s were measured in the case of cyanoethylpullulan. A strong correlation is found between the solvents used for the dielectrics, dielectric constant of the insulator, and the field-effect mobility.

We have fabricated fully patterned all-organic thin-film transistors on polyimide substrates using selectively electropolymerized poly (3,4-ethylenedioxythiophene) doped with poly (styrene sulfonate) (PEDOT:PSS) for the source and drain contacts, PEDOT:PSS Baytron P dispersion for the gate electrodes, poly (4-vinyl phenol) or polyvinyl alcohol for the gate dielectric layers, and pentacene or poly (3-butylthiophene) for the organic active layers. We have built top-gate structures with gates printed on top of the gate dielectric layer. Carrier mobilities as large as 0.01 cm2/V s were measured. Functional all-organic transistors have been realized using a simple and potentially inexpensive technology that does not depend on photolithographical processes and that allows the preparation of feature sizes on the micrometer scale.

Currently, one of the most challenging applications for OLEDs is the full color display. The most energy-efficient way to realize light generation in OLEDs is by using phosphorescent emitters. Green and red emitters have already been demonstrated, but the search for blue emitting organic phosphorescent emitters with good color purity is still ongoing with arduous effort. Here we present our work with a new material developed at BASF which allows phosphorescent emission in the deep-blue spectral range. The emitter has an emission maximum at 400 nm, which gives CIE color coordinates of x = 0.16 and y = 0.06. An OLED device made with this new material shows a maximum external quantum efficiency of 1.5 %. The OLED was built in a three layer structure, with the emitting zone being a hybrid guest-host system. As host material we used the optically and electronically inert polymer poly-methyl-methacrylate (PMMA). Because of its lack of charge transport abilities we doped the host material with a high concentration of the triplet emitting material, i.e. the emitter itself is also used as charge transport material.