Influence of a Π‐Conjugated Bridging Ligand in Light‐Emitting Electrochemical Cells (LEECs)

• Published in: ChemistrySelect (Weinheim) 2018-07, Vol.3 (25), p.7226-7230
• Main Authors: Bideh, Babak Nemati, Shahroosvand, Hashem
• Format: Article
• Language: English
• Subjects: Binuclear complex; LEEC; Π-conjugated ligand
• ISSN: 2365-6549; 2365-6549
• DOI: 10.1002/slct.201800495

By introducing a new π‐conjugated bridging ligand, the electroluminescence metrics of light‐emitting electrochemical cell (LEEC) based on their ruthenium phenanthroimidazole complexes were dramatically improved with respect to its non‐conjugated bridging ligand, achieving a decrease of turn‐on voltage from 3.1 to 2.5 V as well as a long red shift to near infrared region in electroluminescence spectrum. Moreover, the addition of aromaticity into the bridging ligand make the increasing of the external quantum efficiency (EQE) from 0.68% to 0.89% as well as lifetime (t1/2) of electroluminescence emission from 1140 to 1171 (s). Obtained results indicated the exclusive position of bridging ligand to enhance the electroluminescence properties of emitters which that has not been investigated in details to date. Influence of Π‐conjugated bridging ligand of binuclear ruthenium phenanthroimidazole complexes on the electroluminescence metrics in light‐emitting electrochemical cell (LEEC) has been studied. In comparision with the non‐conjugaed briding ligand, ruthenium complexes containing Π‐conjugated bridging ligand shown better external quantom efficieny (EQE), reaching to 0.69% as well as decreasing of turn on voltage from 3.1 to 2.5 V. In particular, the electroluminesce spectrum of Π‐conjugated bridging ligand was also showd a long red shift, exending to near‐infrard region.