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  4. Versatile Electroluminescence Color-Tuning Strategy of an Efficient Light-Emitting Electrochemical Cell (LEC) by an Ionic Additive
 
research article

Versatile Electroluminescence Color-Tuning Strategy of an Efficient Light-Emitting Electrochemical Cell (LEC) by an Ionic Additive

Karimi, Soheila
•
Shahroosvand, Hashem
•
Nia, Narges Yaghoobi
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December 14, 2022
Inorganic Chemistry

The color-tuning strategies of solid-state light-emitting devices (ss-LEDs) are mainly focused on engineering molecular structures. In this paper, for the first time, we developed a facile strategy for tuning the electroluminescence (EL) color from orange to green through the addition of the ionic additive TBAP (tetrabutylammonium perchlorate). To achieve the active ionic emissive compound for use in a light-emitting electrochemical cell (LEC), the neutral biscyclometalated bromo tetrazole iridium(III) [Ir(ppy)2(BrTz)] was exchanged to its cationic complex, [Ir(ppy)2(BrTz-Me)]ClO4 (ppy = 2-phenyl pyridine, BrTz = 4-bromo-2-pyridine tetrazole, BrTz-Me = 4-bromo-2pyridine methyl tetrazole) with a new synthetic strategy. This method allows employing neutral Ir-cyclometalated complexes, which are ruled out for use in LECs because of their non-ionic behaviors. In the following, an LEC based on the new cationic [Ir(ppy)2(BrTz-Me)]ClO4 as the emissive layer was fabricated between the FTO (fluorine-doped tin oxide) anode and Ga:In alloy cathode without using any additive or polymers, which makes this configuration the simplest ss-LED so far. By adding the ionic additives, the electroluminescence characteristics of [Ir(ppy)2(BrTz-Me)]ClO4 were dramatically increased, including luminance (L) from 162.8 cd/m2 for the device with an additive to 212.9 and 355.9 cd/m2 for devices containing LiTFSI (bis(trifluoromethane)sulfonamide lithium salt) and TBAP, respectively. In particular, when TBAP was added to the [Ir(ppy)2(BrTz-Me)]ClO4 complex, the irradiance was significantly increased from 166.4 to 220.8 mu W/cm2 with an efficacy of 1.78 cd/A and external quantum efficiency (EQE) value of 2.14%. The obtained EL results clearly showed that adding TBAP and LiTFSI significantly improved the electroluminescence characteristics and tuned the electroluminescence color.

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Type
research article
DOI
10.1021/acs.inorgchem.2c02165
Web of Science ID

WOS:000897731000001

Author(s)
Karimi, Soheila
Shahroosvand, Hashem
Nia, Narges Yaghoobi
Di Carlo, Aldo
Nazeeruddin, Mohammad Khaja  
Date Issued

2022-12-14

Publisher

AMER CHEMICAL SOC

Published in
Inorganic Chemistry
Volume

61

Issue

51

Start page

20734

End page

20742

Subjects

Chemistry, Inorganic & Nuclear

•

Chemistry

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cyclometalated iridium(iii) complexes

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transition-metal-complexes

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solid-state

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ancillary ligand

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blue phosphorescence

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ir(iii) complexes

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room-temperature

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recent progress

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green

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yellow

Editorial or Peer reviewed

REVIEWED

Written at

EPFL

EPFL units
GMF  
Available on Infoscience
January 2, 2023
Use this identifier to reference this record
https://infoscience.epfl.ch/handle/20.500.14299/193562
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