Enhanced Light Out-Coupling Efficiency of Organic Light-Emitting Diodes with Self-Organized Microlens Arrays

Abstract

A method for enhancing the light out-coupling efficiency of organic light-emitting diodes (OLEDs) by incorporating microlens arrays (MLAs) is demonstrated. MLAs made of prepolymer NOA65 were fabricated on a substrate prepatterned by the microcontact printing of hydrophobic self-assembled monolayers (SAMs). Owing to the hydrophobic effect, the lens material was self-organized on the hydrophilic regions. After assembling the MLA onto an OLED, the optical measurement showed that the light out-coupling efficiency of the OLED with MLAs is increased without any apparent color shift.

Tunable microcavities in organic light-emitting diodes by way of low-refractive-index polymer doping

“…The luminance distribution was noncircular in symmetry because of the rectangular shape of the PLEDs; the active area was 0.1 cm 2 (0.2 cm  0.5 cm) [9]. The corresponding luminance at 0°t o 180°azimuthal angle and at different inclination angles was also revealed in Fig.…”

“…Many approaches, including using high-refractiveindex substrates [3,7], microlense arrays [8,9], photonic crystals [10], and plasmonic nanostructures [11], have been studied to enhance g out . Meanwhile, the conventional structure of OLEDs naturally behaves as a weak microcavity because the dimension of their functional layers is similar to the wavelength of the emitting photons.…”

Rapid laser fabrication of microlens array using colorless liquid photopolymer for AMOLED devices

“…The structural layers of the OLED consisted of a Circular Polarizer (CPL), a Cathode, Electron Injection Layer (EIL), an Electron Transfer Layer (ETL), a Hole Blocking Layer (HBL), an Emission Material Layer (EML), a Hole Transfer Layer (HTL), a Hole Injection Layer (HIL), an anode and a reflective layer from the bottom. The luminance of an OLED device depends on the viewing angles such as inclination and azimuthal angles [21]. In addition, the light trapped in the OLED because of Total Internal Reflection (TIR) emits from the side or is absorbed by the organic layer again.…”

P‐176: Effect of Cathode Reflectivity on Light Enhancement of White OLEDs with Microlens Structure

“…The alternative solution is to use micrometer-scale array lenses (microlens) [8] which can avoid the alignment problem with WOLEDs and thus it has been extensively used to improve light outcopling efficiency recently [9][10][11][12][13]. Accordingly, microlens will become an indispensable element for construction of future lighting fixtures.…”