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<p>Enhanced efficiency in flexible blue phosphorescent organic light-emitting diodes (PhOLEDs)&#xa0;through the incorporation of two distinct blue emissive layers (EMLs) in the same device is reported. These EMLs employed different host materials while utilizing the same blue-emitting phosphorescent dye bis[2-(4,6-difluorophenyl)pyridinato-C2,N](picolinato) Iridium (FIrpic) as guest. Tris(4-carbazoyl-9-ylphenyl)amine (TCTA) and 3,3′-Di(9H-carbazol-9-yl)-1,1′-biphenyl (mCBP) were used as host materials for the respective EMLs. The doping concentration of FIrpic was systematically optimized by varying its wt% ratio in the EMLs and the optimum concentration of FIrpic was found to be 20&#xa0;wt%. The blue OLEDs based on single-EML of TCTA:FIrpic (20&#xa0;wt%) exhibited a maximum current efficiency (CE<sub>max</sub>) of 19.2&#xa0;cd/A, whereas those based on mCBP:FIrpic (20&#xa0;wt%) single-EML showed CE<sub>max</sub> of 13.9&#xa0;cd/A. The PhOLEDs fabricated using dual-EMLs comprising sequentially deposited TCTA:FIrpic and mCBP:FIrpic EMLs demonstrated a significantly improved CE<sub>max</sub> of 23.9&#xa0;cd/A. This performance surpassed that of the&#xa0;devices with a single-EML, highlighting the effectiveness of the dual -EMLs strategy in enhancing device efficiency. The PhOLEDs incorporating dual-EMLs exhibited not only improved efficiency but also improved operational stability compared to those based on single-EML. Under continuous operation, half lifetime (<i>T</i><sub>50</sub>) of PhOLEDs with dual-EMLs was determined to be 540&#xa0;min, whereas the <i>T</i><sub>50</sub> for PhOLEDs based on TCTA:FIrpic and mCBP:FIrpic single- EML were determined to be around 120 and 30&#xa0;min respectively. The flexible PhOLEDs have also shown good electroluminescence (EL) characteristics even after repeated 1000 bending cycles at an angle of 90°.</p>

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Improved efficiency and operational lifetime of flexible blue phosphorescent OLEDs by dual emissive layers

  • 期刊论文

  • 发表日期：

    2026年7月8日

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  • Aparna Tripathi,
  • Pankaj Kumar,
  • V. S. Pandey

摘要

Enhanced efficiency in flexible blue phosphorescent organic light-emitting diodes (PhOLEDs) through the incorporation of two distinct blue emissive layers (EMLs) in the same device is reported. These EMLs employed different host materials while utilizing the same blue-emitting phosphorescent dye bis[2-(4,6-difluorophenyl)pyridinato-C2,N](picolinato) Iridium (FIrpic) as guest. Tris(4-carbazoyl-9-ylphenyl)amine (TCTA) and 3,3′-Di(9H-carbazol-9-yl)-1,1′-biphenyl (mCBP) were used as host materials for the respective EMLs. The doping concentration of FIrpic was systematically optimized by varying its wt% ratio in the EMLs and the optimum concentration of FIrpic was found to be 20 wt%. The blue OLEDs based on single-EML of TCTA:FIrpic (20 wt%) exhibited a maximum current efficiency (CEmax) of 19.2 cd/A, whereas those based on mCBP:FIrpic (20 wt%) single-EML showed CEmax of 13.9 cd/A. The PhOLEDs fabricated using dual-EMLs comprising sequentially deposited TCTA:FIrpic and mCBP:FIrpic EMLs demonstrated a significantly improved CEmax of 23.9 cd/A. This performance surpassed that of the devices with a single-EML, highlighting the effectiveness of the dual -EMLs strategy in enhancing device efficiency. The PhOLEDs incorporating dual-EMLs exhibited not only improved efficiency but also improved operational stability compared to those based on single-EML. Under continuous operation, half lifetime (T50) of PhOLEDs with dual-EMLs was determined to be 540 min, whereas the T50 for PhOLEDs based on TCTA:FIrpic and mCBP:FIrpic single- EML were determined to be around 120 and 30 min respectively. The flexible PhOLEDs have also shown good electroluminescence (EL) characteristics even after repeated 1000 bending cycles at an angle of 90°.