[Effect of mixed interface on the performance of solution-processed phosphorescent OLEDs]

Area of Science:

• Organic electronics
• Materials science
• Device physics

Context:

• Solution-processed phosphorescent organic light-emitting devices (PhOLEDs) are crucial for advanced display and lighting applications.
• Efficient charge injection and transport at interfaces within PhOLEDs are critical for device performance.
• Existing interfaces between hole blocking layers (HBL) and electron transport layers (ETL) can limit device efficiency.

Purpose:

• To improve electron injection and transport at the HBL/ETL interface in PhOLEDs.
• To fabricate a mixed interface layer (MIL) by co-doping BCP and Alq3.
• To investigate the effect of MIL doping ratios on device performance.

Summary:

• A 10nm-thick MIL was created by co-doping 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP) and tris(8-quinolinolato) aluminum (Alq3) between the HBL and ETL.
• Devices with the MIL exhibited significantly higher luminance and current density compared to devices with a typical interface.
• For example, at 10V, luminance power increased from 1.03 μW to 3.64 μW, and current density rose from 5.13 mA/cm² to 18.1 mA/cm².

Impact:

• The MIL reduces electron accumulation at the interface by lowering the electron injection energy barrier and transport mobility.
• This leads to an increased electron population within the emissive layer, resulting in higher luminance and current density.
• The findings offer a promising strategy for enhancing the efficiency and performance of solution-processed PhOLEDs.