Patterned microlens array for efficiency improvement of small-pixelated organic light-emitting devices.

Area of Science:

• Optoelectronics
• Materials Science
• Photonics

Background:

• Organic light-emitting diodes (OLEDs) are crucial for displays and lighting.
• Light extraction efficiency is a key parameter for OLED performance.
• Microlens arrays are explored to enhance light extraction.

Purpose of the Study:

• To investigate the optical characteristics of OLEDs with patterned microlens array films.
• To analyze the impact of pixel size and microlens geometry on light extraction.
• To develop an optimized microlens array for improved OLED efficiency.

Main Methods:

• Experimental and theoretical investigation of OLEDs with varying pixel sizes.
• Fabrication and testing of regular and center-hollowed microlens array films.
• Measurement of luminance, luminous current efficiency, and luminous power efficiency.

Main Results:

• Regular microlens arrays can decrease luminance for small OLED pixels (close to microlens dimensions).
• A center-hollowed microlens array significantly enhances light extraction for small-pixelated OLEDs.
• An 87% luminance enhancement was achieved for a 0.1x0.1 mm² OLED pixel using the proposed array.

Conclusions:

• The design of microlens arrays must consider the OLED pixel size for effective light extraction.
• Center-hollowed microlens arrays offer a promising strategy to improve the efficiency of small-pixelated OLEDs.
• This approach provides a significant enhancement in luminance and efficiency for OLED devices.