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Spatial Control of p-n Junction in an Organic Light-Emitting Electrochemical Transistor
Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.ORCID iD: 0000-0001-5365-6140
Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.ORCID iD: 0000-0001-8845-6296
Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.ORCID iD: 0000-0003-4791-4785
2012 (English)In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 134, no 2, 901-904 p.Article in journal (Refereed) Published
Abstract [en]

Low-voltage-operating organic electrochemical light-emitting cells (LECs) and transistors (OECTs) can be realized in robust device architectures, thus enabling easy manufacturing of light sources using printing tools. In an LEC, the p-n junction, located within the organic semiconductor channel, constitutes the active light-emitting element. It is established and fixated through electrochemical p- and n-doping, which are governed by charge injection from the anode and cathode, respectively. In an OECT, the electrochemical doping level along the organic semiconducting channel is controlled via the gate electrode. Here we report the merger of these two devices: the light-emitting electrochemical transistor, in which the location of the emitting p-n junction and the current level between the anode and cathode are modulated via a gate electrode. Light emission occurs at 4 V, and the emission zone can be repeatedly moved back and forth within an interelectrode gap of 500 mu m by application of a 4 V gate bias. In transistor operation, the estimated on/off ratio ranges from 10 to 100 with a gate threshold voltage of -2.3 V and transconductance value between 1.4 and 3 mu S. This device structure opens for new experiments tunable light sources and LECs with added electronic functionality.

Place, publisher, year, edition, pages
American Chemical Society , 2012. Vol. 134, no 2, 901-904 p.
National Category
Engineering and Technology
URN: urn:nbn:se:liu:diva-76542DOI: 10.1021/ja210936nISI: 000301084300041OAI: diva2:515120
Funding Agencies|Swedish Government||Swedish Foundation for Strategic Research (OPEN)||VINNOVA (PEA-PPP)||Tillvaxtverket||Knut and Alice Wallenberg Foundation||Onnesjo Foundation||Available from: 2012-04-12 Created: 2012-04-11 Last updated: 2015-05-06
In thesis
1. Light-Emitting Electrochemical Transistors
Open this publication in new window or tab >>Light-Emitting Electrochemical Transistors
2014 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Since the discovery of conductive polymers in 1977, the implementation of organic conjugated materials in electronic applications has been of great interest in both industry and academia. The goal of organic electronics is to realize large-area, inexpensive and mechanically-flexible electronic applications.

Organic light emitting diodes (OLEDs), as the first commercial product made from organic conjugated polymers, have successfully demonstrated that organic electronics can make possible a new generation of modern electronics. However, OLEDs are highly sensitive to materials selection and requires a complicated fabrication process. As a result, OLEDs are expensive to fabricate and are not suitable for low-cost printing or roll-to-roll process.

This thesis studies an alternative to OLEDs: light-emitting electrochemical cells (LECs). The active materials in an LEC consist of a conjugated light-emitting polymer (LEP) and an electrolyte. Taking advantage of electrochemical doping of the LEP, an LEC features an in-situ formed emissive organic p-n junction which is easy to fabricate. We aim to control the electrochemical doping profile by employing a “gate” terminal on top of a conventional LEC, forming a lightemitting electrochemical transistor (LECT). We developed three generations of LECTs, in which the position of the light-emitting profile can be modified by the voltage applied at the gate electrode, as well as the geometry of the gate materials. Thus, one can use this structure to achieve a centered light-emitting zone to maximize the power-conversion efficiency. Alternatively, LECTs can be used for information display in a highly integrated system, as it combines the simultaneous modulation of photons and electrons.

In addition, we use multiple LECs to construct reconfigurable circuits, based on the reversible electrochemical doping. We demonstrate an LEC-array where several different circuits can be created by forming diodes with different polarity at different locations. The thereby formed circuitry can be erased and turned into circuitry with other functionality. For example, the diodes of a digital AND gate can be re-programmed to form an analogue voltage limiter. These reprogrammable circuits are promising for fully-printed and large-area reconfigurable circuits with facile fabrication.

Place, publisher, year, edition, pages
Linköping: Linköping University Electronic Press, 2014. 57 p.
Linköping Studies in Science and Technology. Dissertations, ISSN 0345-7524 ; 1582
National Category
Natural Sciences
urn:nbn:se:liu:diva-104925 (URN)10.3384/diss.diva-104925 (DOI)978-91-7519-382-3 (print) (ISBN)
Public defence
2014-03-21, K2, Kåkenhus, Campus Norrköping, Linköpings universitet, Norrköping, 10:15 (English)
Available from: 2014-03-03 Created: 2014-03-03 Last updated: 2015-05-06Bibliographically approved

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