The isomeric effect of thienopyridazine-based iridium complexes

Three tris-cyclometalated iridium( iii ) complexes based on different thienopyridazine isomeric ligands were successfully synthesized. The influence of isomerism on material properties was comprehensively evaluated. The thieno[2,3- d ]pyridazine based isomeric complexes IrM and IrP have similar phot...

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Published inJournal of materials chemistry. C, Materials for optical and electronic devices Vol. 12; no. 17; pp. 6248 - 6256
Main Authors Zhang, Jia-Ling, Zhang, Fu-Jun, Xu, Hui-Hui, Li, Zheng-Ze, Sheng, Ren, Zhang, Qian-Feng, Tong, Bi-Hai, Chen, Ping, Kong, Hui
Format Journal Article
LanguageEnglish
Published Cambridge Royal Society of Chemistry 02.05.2024
Subjects
Chemical bonds
Electron transport
Energy gap
Hydrogen bonding
Iridium compounds
Material properties
Maximum power
Phosphorescence
Power efficiency
Pyridazines
Quantum efficiency
Solubility
Stability
Transport properties
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Summary:Three tris-cyclometalated iridium( iii ) complexes based on different thienopyridazine isomeric ligands were successfully synthesized. The influence of isomerism on material properties was comprehensively evaluated. The thieno[2,3- d ]pyridazine based isomeric complexes IrM and IrP have similar photophysical properties. However, sulfur atoms regulate intramolecular hydrogen bonding in complex IrM , leading to differences in other properties. Complex IrM exhibits ambipolar transport properties, good solubility and excellent stability ( T d = 425 °C), while IrP shows electronic transport properties, bad solubility and moderate stability ( T d = 374 °C). The thieno[3,4- d ]pyridazine based complex IrC has very low stability ( T d = 214 °C) and significantly reduced optical energy gap compared to other isomers, making it almost non-luminescent. Complexes IrM and IrP are excellent yellow phosphorescent dopants for OLED application, and the maximum power efficiency (PE) and external quantum efficiency (EQE) based on them were 76.0 lm W −1 , 26.7% and 73.5 lm W −1 , 28.3%, respectively. This indicates that thieno[2,3- d ]pyridazine based complexes have great potential for application in full-color displays and solid-state lighting. Complex IrM exhibited a high PLQY of 0.99, a T d of 425 °C and a peak EQE of 26.7%.
Bibliography:Electronic supplementary information (ESI) available. CCDC
For ESI and crystallographic data in CIF or other electronic format see DOI
2278181
https://doi.org/10.1039/d4tc00289j
ISSN:2050-7526
2050-7534
DOI:10.1039/d4tc00289j