Highly enhanced light extraction for organic light emitting diodes by self-assembly microlens-array films

• Published in: Journal of luminescence Vol. 263; p. 119986
• Main Authors: Lin, Bo-Yen, Lin, Ya-Xun, Lin, Shao-Ju, Lin, Yi-Yen, Chen, Su-Hua, Wei, Mao-Kuo
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.11.2023
• Subjects: Light extraction; Microlens; Organic light-emitting diodes; Light extraction; Microlens; Organic light-emitting diodes
• ISSN: 0022-2313; 1872-7883
• DOI: 10.1016/j.jlumin.2023.119986

Light extraction efficiency (LEE) and angular-spectrum stability of organic light emitting diode (OLED) are significantly improved by using self-assembly microlens-array films (MAFs) made of a monolayer based on silica microspheres and acrylic resin as light extractor. The close-packed light MAFs with a high fill factor of 71.42% was uniformly fabricated by a facile and low-cost solution process of spin-coating. The MAFs feature highly transmissive with transmittance of 86.2–90.6% and also high haze of 78.9–82.4% in UV–Vis regime. External quantum efficiency (EQE) of OLED with MAFs was significantly improved from 3.04 to 5.04%, corresponding to an enhancement of 66% compared with reference OLED. The small angular shift of CIE-indices is in a range of (0.008, 0.004), while viewing angle changes from 0° to 60°. Besides, the origin of high LEE and angular-spectrum stability was due to high scattering effect induced by high haze, leading to a Lambertian emissive profile. Notably, the proposed fabrication for the MAFs is simple and scalable, which was believed to be a promising approach for display and lighting applications. [Display omitted] •The silica based MAFs with high fill factor, transmittance and haze of ∼71.4%, 90% and 80% in at wavelength from 380 to 780 nm.•High light extraction in EQE enhancement of 66% and angular-spectrum stability was achieved for OLED.•The proposed fabrication for MAFs is facile and scalable.•The origin of high LEE and angular-spectrum stability was deduced from high scattering effect.