All-organic electrochemical device with bi-stable and dynamic functionality

• We will present organic electrochemical transistors that show both bi-stable and dynamic current modulation. In electrochemical devices, both ions and electrons are used as charge carriers. The device is all-organic and has been realized using common printing techniques, such as screen-printing. As the substrate, both cellulose-based paper and polyester foil have been used. PEDOT:PSS (poly(3,4-ethylenedioxythiophene):Poly(styrene sulphonic acid)) is used as the conducting and electrochemical active material. PEDOT:PSS is switched between different redox states, corresponding to semi-conducting and conducting states. Operating voltages is below 2V and on/off ratios up to 105 have been reached (typical value is 5000). The operation of these devices does not depend on any critical dimensions, typical dimensions used are around 200 microns. With a certain geometrical design the dynamic transistor can be employed for frequency doubling. For the bi-stable transistor the modulation of the current is done by direct electronic contact, compared to the dynamic transistor that is modulated by induction of electrochemistry. The electrolyte in these devices can either be solidified or a liquid. The bi-stable device in combination with a layer of Nafion® as electrolyte demonstrates humidity sensor functionality. Since substrates based on paper and common printing techniques can be used for fabrication, this give rise to an environmental friendly and non-expensive device setup.

Nyckelord

Electrochemistry

Organic transistor sensor

Poly(3

4-ethylenedioxythiophene) (PEDOT)

Poly(styrene sulphonic acid) (PSS)

Printing

TECHNOLOGY

TEKNIKVETENSKAP

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