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New concepts for light emitting transistors

Hepp, Aline and Ahles, Marcus and Heil, Holger and Schmechel, Roland and Weiler, Ulrich and Mayer, Thomas and Jaegermann, Wolfram Dodabalapur, Ananth (ed.) (2004):
New concepts for light emitting transistors.
5522In: Organic field-effect transistors III, In: SPIE Proceedings, Bellingham, Wash., SPIE, Denver, Colorado, USA, August 02, 2004, p. 53, [Online-Edition: http://proceedings.spiedigitallibrary.org/proceeding.aspx?ar...],
[Conference or Workshop Item]

Abstract

In this study we report on new concepts to generate light emission in organic thin film transistors. The initial physical understanding of light emission from tetracene based field-effect transistors was proposed to be originated from a strong underetching of the drain and source electrodes. This underetched electrodes in combination with the evaporated tetracene is thereby believed to generate a virtual OLED at the drain electrode. Accumulated holes have to leave the gate oxide interface to reach the drain electrode by crossing the bulk of the organic semiconductor. Light then occurs by injection of electrons in a large electric field in the bulk. Today's transistors do not show the underetching anymore but are still emitting light only at the drain electrode, again supporting the initial interpretation of a defect state at the edge of the drain electrode. In this context the question how electrons can overcome a potential barrier of 2.7 eV is still open. Therefore an investigation of the gold tetracene interface by UPS and XPS techniques has been started and preliminary data indicate the unexpected result that the barrier for electrons is comparable to that for holes. In a further step the generation of an ambipolar transistor by interface doping with calcium was tried and an n-type pentacene transistor could be fabricated but the strategy failed for tetracene. Finally an electrochemical interface doping was performed by the application of Lithium triflate in PEO to a thin interface layer between gate oxide and tetracene. This leads to light emission but unfortunately also to the loss of the gate voltage influence. Based on these results a possible strategy will be presented.

Item Type: Conference or Workshop Item
Erschienen: 2004
Editors: Dodabalapur, Ananth
Creators: Hepp, Aline and Ahles, Marcus and Heil, Holger and Schmechel, Roland and Weiler, Ulrich and Mayer, Thomas and Jaegermann, Wolfram
Title: New concepts for light emitting transistors
Language: English
Abstract:

In this study we report on new concepts to generate light emission in organic thin film transistors. The initial physical understanding of light emission from tetracene based field-effect transistors was proposed to be originated from a strong underetching of the drain and source electrodes. This underetched electrodes in combination with the evaporated tetracene is thereby believed to generate a virtual OLED at the drain electrode. Accumulated holes have to leave the gate oxide interface to reach the drain electrode by crossing the bulk of the organic semiconductor. Light then occurs by injection of electrons in a large electric field in the bulk. Today's transistors do not show the underetching anymore but are still emitting light only at the drain electrode, again supporting the initial interpretation of a defect state at the edge of the drain electrode. In this context the question how electrons can overcome a potential barrier of 2.7 eV is still open. Therefore an investigation of the gold tetracene interface by UPS and XPS techniques has been started and preliminary data indicate the unexpected result that the barrier for electrons is comparable to that for holes. In a further step the generation of an ambipolar transistor by interface doping with calcium was tried and an n-type pentacene transistor could be fabricated but the strategy failed for tetracene. Finally an electrochemical interface doping was performed by the application of Lithium triflate in PEO to a thin interface layer between gate oxide and tetracene. This leads to light emission but unfortunately also to the loss of the gate voltage influence. Based on these results a possible strategy will be presented.

Title of Book: SPIE Proceedings
Series Name: Organic field-effect transistors III
Volume: 5522
Place of Publication: Bellingham, Wash.
Publisher: SPIE
Uncontrolled Keywords: Calcium, Doping, Electrodes, Electrons, Gold, Interfaces, Lithium, Organic light emitting diodes, Organic semiconductors, Oxides.
Divisions: 11 Department of Materials and Earth Sciences > Material Science > Electronic Materials
11 Department of Materials and Earth Sciences > Material Science > Surface Science
11 Department of Materials and Earth Sciences > Material Science
11 Department of Materials and Earth Sciences
Event Location: Denver, Colorado, USA
Event Dates: August 02, 2004
Date Deposited: 20 Nov 2008 08:19
Official URL: http://proceedings.spiedigitallibrary.org/proceeding.aspx?ar...
Identification Number: doi:10.1117/12.566541
License: [undefiniert]
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