High efficiency red top-emitting micro-cavity organic light emitting diodes

Area of Science:

• Optoelectronics
• Materials Science
• Photonics

Background:

• Micro-cavity effects are crucial for enhancing light extraction in organic light-emitting diodes (OLEDs).
• Tandem OLEDs offer potential for improved efficiency and color tuning.
• Accurate optical simulation is vital for predicting and optimizing device performance.

Purpose of the Study:

• To compare optical simulation results with experimental data for red tandem top-emitting organic light-emitting diodes (TEOLEDs).
• To validate the accuracy of optical simulations in predicting micro-cavity effects and device performance.
• To investigate the impact of emissive layer positions on radiance and color coordinates.

Main Methods:

• Fabrication of red tandem TEOLED devices.
• Optical simulation using established models to predict device performance.
• Measurement of current efficiency, external quantum efficiency, and color coordinates of fabricated devices.
• Comparison of simulated and experimental optical and electrical characteristics.

Main Results:

• Optical simulations predicted two possible emissive layer (EML) positions within the second-order micro-cavity, yielding similar radiance near National Television System Committee (NTSC) color coordinates.
• Simulated current efficiency and external quantum efficiency were 98.8 cd/A and 22.6%, respectively.
• Fabricated devices demonstrated comparable performance with 95.8 cd/A current efficiency and 26.5% external quantum efficiency.

Conclusions:

• The study validates the predictive capability of optical simulations for red tandem TEOLEDs.
• Experimental results closely align with simulation predictions, confirming the micro-cavity design.
• The findings support the use of optical simulations for optimizing TEOLED performance and design.