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Dynamic Doping in Planar Ionic Transition Metal Complex‐Based Light‐Emitting Electrochemical Cells
Author(s) -
Meier Sebastian B.,
van Reenen Stephan,
Lefevre Bastien,
Hartmann David,
Bolink Henk J.,
Winnacker Albrecht,
Sarfert Wiebke,
Kemerink Martijn
Publication year - 2013
Publication title -
advanced functional materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.069
H-Index - 322
eISSN - 1616-3028
pISSN - 1616-301X
DOI - 10.1002/adfm.201202689
Subject(s) - materials science , kelvin probe force microscope , cathode , drop (telecommunication) , doping , ionic bonding , electrochemical cell , quenching (fluorescence) , photoluminescence , optoelectronics , anode , electrode , electrochemistry , microscopy , planar , fluorescence , nanotechnology , analytical chemistry (journal) , optics , ion , chemistry , atomic force microscopy , telecommunications , physics , computer graphics (images) , organic chemistry , chromatography , computer science
Using a planar electrode geometry, the operational mechanism of iridium(III) ionic transition metal complex (iTMC)‐based light‐emitting electrochemical cells (LECs) is studied by a combination of fluorescence microscopy and scanning Kelvin probe microscopy (SKPM). Applying a bias to the LECs leads to the quenching of the photoluminescence (PL) in between the electrodes and to a sharp drop of the electrostatic potential in the middle of the device, far away from the contacts. The results shed light on the operational mechanism of iTMC‐LECs and demonstrate that these devices work essentially the same as LECs based on conjugated polymers do, i.e., according to an electrochemical doping mechanism. Moreover, with proceeding operation time the potential drop shifts towards the cathode coincident with the onset of light emission. During prolonged operation the emission zone and the potential drop both migrate towards the anode. This event is accompanied by a continuous quenching of the PL in two distinct regions separated by the emission line.