Novel phenanthroimidazole-based blue AIEgens: reversible mechanochromism, bipolar transporting properties, and electroluminescenceElectronic supplementary information (ESI) available: X-ray crystallographic information files. CCDC 1818717 (2PPI-TPE). For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c8nj01006d

• Main Authors: Wang, Zhong-Yi, Zhao, Jue-Wen, Li, Peng, Feng, Tong, Wang, Wen-Jian, Tao, Si-Lu, Tong, Qing-Xiao
• Format: Article
• Language: English
• ISSN: 1144-0546; 1369-9261
• DOI: 10.1039/c8nj01006d

Multifunctional materials are crucial and have promising applications in a wide range of organic electronics. Herein, we designed and synthesized two bipolar blue molecules named 2-(4-(4,5-diphenyl-2-(4-(1,2,2-triphenylvinyl)phenyl)-1 H -imidazol-1-yl)phenyl)-1-phenyl-1 H -phenanthro[9,10- d ]imidazole ( PPI-PIM-TPE ) and 1-phenyl-2-(4-(2-(4-(1,2,2-triphenylvinyl)phenyl)-1 H -phenanthro[9,10- d ]imidazol-1-yl)phenyl)-1 H -phenanthro[9,10- d ]imidazole ( 2PPI-TPE ) with aggregation-induced emission (AIE) and mechanochromism characteristics. They both have good thermal stability ( T d is 505 °C for PPI-PIM-TPE and 510 °C for 2PPI-TPE ), strong AIE properties and reversible mechanochromism. The quantum yields in the solid state were as high as 61.9% for PPI-PIM-TPE and 73.4% for 2PPI-TPE . In addition, the two pristine solid powders are white and emit blue light. After grinding, the solid becomes yellow and emits blue-green emission. The color changes are reversible by solvent fuming. The change in emission color can be observed by the naked eye, demonstrating that they are typical mechanochromic materials. Non-doped blue OLEDs based on 2PPI-TPE exhibit an external quantum efficiency (EQE), current efficiency (CE) and power efficiency (PE) of 2.48%, 6.46 cd A −1 and 4.72 lm W −1 , respectively. The doped device based on 2PPI-TPE as a dopant emitter exhibits a higher EQE, CE and PE of 3.55%, 6.67 cd A −1 and 5.52 lm W −1 . The performances of the OLEDs with these emitters are among the best of recent reports based on blue materials with AIE and mechanochromism simultaneously. Multifunctional materials are crucial and have promising applications in a wide range of organic electronics.