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Stable and Efficient Solid‐State Light‐Emitting Electrochemical Cells Based on a Series of Hydrophobic Iridium Complexes
Author(s) -
Costa Rubén D.,
Ortí Enrique,
Tordera Daniel,
Pertegás Antonio,
Bolink Henk J.,
Graber Stefan,
Housecroft Catherine E.,
Sachno Ludmila,
Neuburger Markus,
Constable Edwin C.
Publication year - 2011
Publication title -
advanced energy materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 10.08
H-Index - 220
eISSN - 1614-6840
pISSN - 1614-6832
DOI - 10.1002/aenm.201000069
Subject(s) - iridium , materials science , quantum yield , ionic bonding , photoluminescence , electrochemistry , ligand (biochemistry) , electrochemical cell , visible spectrum , bipyridine , photochemistry , chemistry , fluorescence , crystallography , electrode , optoelectronics , ion , optics , catalysis , organic chemistry , physics , biochemistry , receptor , crystal structure
Light‐emitting electrochemical cells (LECs) based on ionic transition‐metal complexes (iTMCs) exhibiting high efficiency, short turn‐on time, and long stability have recently been presented. Furthermore, LECs emitting in the full range of the visible spectrum including white light have been reported. However, all these achievements were obtained individually, not simultaneously, using in each case a different iTMC. In this work, device stability is maintained by employing intrinsically stable ionic iridium complexes, while increasing the complex and the device quantum yields for exciton‐to‐photon conversion. This is done by sequentially modifying the archetype ionic iridium complex [Ir(ppy) 2 (bpy)][PF 6 ], where Hppy is 2‐phenylpyridine and bpy is 2,2'‐bipyridine, with methyl and phenyl groups on the bpy ligand. A full photophysical and theoretical description of a series of four complexes, including the archetype as a reference, is presented and their performance in LECs is characterized. Upon selecting suitable substituents, a twofold increase is obtained in the photoluminescence quantum yield in a solid film. This is reflected in a significant increase in the efficiency over time curve for LECs using this complex.