A silane-based host material with improved electron transport properties for phosphorescent OLEDs with high efficiency and low efficiency roll-off

A dibenzosilole-based host material was designed and characterized. The material, 9,9′-(5,5-diphenyl-5H-dibenzo[b, d]silole-2,8-diyl)bis(9H-carbazole) (S-SiCz), to enhance the electron transport properties rigidity by coupling two phenyl units of tetraphenyl silane a strong hole type bis(4-(9H-carbazol-9-yl)phenyl)diphenylsilane host. device efficiency roll-off improved considerably balancing carriers in phosphorescent organic light-emitting diodes (PhOLEDs), driving voltage at high luminance reduced. red green PhOLEDs exhibited external quantum efficiencies (EQEs) 23.8% 24.9%, respectively, relieved roll-off. In addition, S-SiCz used as an with 3,3′-di(9H-carbazol-9-yl)-1,1′-biphenyl maximum EQEs using mixed were 26.0% 25.5%, EQE values 18% 6%, respectively. Therefore, planarization design strategy is effective for better performance.