Highly-efficient tandem organic light-emitting device employing bis-4,6-(3,5-di-3-pyridylphenyl)-2-methylpyrimi-dine doped with cesium azide in charge generation unit

摘要

In this research, we have investigated the charge generation and electron injection processes in charge generation unit (CGU) consisting of CsN_3-doped Bis-4, 6-(3, 5-di-3-pyridylphenyl)-2-methylpyrimi-dine (CsN_3:B_3PYMPM)/Al/1, 4, 5, 8, 9, 11-Hexaazatriphenylene-hexacarbonitrile (HAT-CN). By employing this CGU, a high-efficiency phosphorescent tandem device achieving best efficiencies of 164.3 cd/A, 46.51% and 109.8 lm/W has been realized. Particularly, in addition to the improvement in current efficiency by more than two times, the tandem device has better power efficiency compared to the corresponding single-unit device at the same current density. Simultaneously, an efficient tandem white OLED showing high color stability and warm white emission over a wide range of luminance has been also fabricated.