High efficiency green OLEDs based on homoleptic iridium complexes with steric phenylpyridazine ligandsElectronic supplementary information (ESI) available. CCDC 1812579, 1812580 and 1812583. For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c8dt02781a

• Main Authors: Tong, Bihai, Wang, Han, Chen, Man, Zhou, Shixiong, Hu, Yuanyuan, Zhang, Qianfeng, He, Gufeng, Fu, Lianshe, Shi, Huatian, Jin, Long, Zhou, Huidong
• Format: Article
• Language: English
• ISSN: 1477-9226; 1477-9234
• DOI: 10.1039/c8dt02781a

A series of steric phenylpyridazine based homoleptic iridium( iii ) complexes ( 1-3 ) have been synthesized with novel one-pot methods. Single X-ray structural analyses are conducted on complexes 1 and 2 to reveal their coordination arrangement. These complexes exhibit a very strong green phosphorescence emission with high quantum yields of over 64%. The relationship between photophysical properties and the substituent nature of the complexes is discussed by density functional theory (DFT) and time-dependent DFT. Self-quenching is significantly reduced for these complexes in solid even at very high concentrations because the sterically hindered bicyclo [2.2.2] oct-2-ene and m -substituted CF 3 spacers in the phosphor molecules lead to minimum bimolecular interactions. Accordingly, the electroluminescence device based on complex 3 exhibits a maximum luminous efficiency of 64.1 cd A −1 with a high EQE of 25.2% at a high doping concentration of 15 wt%. Meanwhile, when neat 3 was adopted as the emitting layer, the non-doped green device gives a state-of-the-art EQE as high as 15.2% (40.1 cd A −1 ) along with CIE coordinates of (0.346, 0.599). The doped and non-doped OLED devices based on 3 exhibit very high EQE of 25.2% and 15.2%, respectively.