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This study utilized cellulose-based external light extraction films to enhance the outcoupling efficiency of organic light-emitting diodes (OLEDs). These films were created through a straightforward fabrication employing the biopolymers hydroxyethyl cellulose (HEC) and tannic acid (TA). We observed that the hydrogen bonding between HEC and TA could spontaneously generate a random microtextured surface on the HEC: TA films. Furthermore, the surface morphology of the HECTA film can be adjusted by varying the TA content. When applying the HECTA films as an external light-extraction layer for OLEDs, we noticed a remarkable improvement in the external quantum efficiency and current efficiency of the OLEDs up to 54% compared to those without the HECTA film. Additionally, the HECTA film displayed an outstanding ability to absorb ultraviolet light. Therefore, it is anticipated that the HECTA film can significantly contribute to prolonging the stability of OLEDs. [ABSTRACT FROM AUTHOR]

The extraction method of surface plasmon polariton (SPP) energy was investigated to assess its ability to improve the outcoupling efficiency of organic light-emitting diodes (OLEDs). A multi-cathode OLED (MC-OLED) structure was used; this structure was composed of a semitransparent cathode (Ag), a high refractive index dielectric layer (WO3), and a reflector (Ag). The dependence of the current efficiency of MC-OLEDs on the thicknesses of the Ag cathode and the WO3dielectric was examined, and optimal thicknesses were identified. Current efficiency can be increased by 20% more than conventional OLEDs by using a 50-nm Ag cathode and a 100-nm WO3dielectric. [ABSTRACT FROM AUTHOR]

Using a buffer layer under the anode, we studied outcoupling enhancement for organic light-emitting diodes. Monolayers of tungsten oxide and titanium oxide were used as the anode buffer layers. Thin anode buffers such as 25 nm and 50 nm tungsten-oxide layers, and a 15 nm titanium-oxide layer noticeably increased the outcoupling. However, thick buffers decreased the outcoupling. The combined effects of the constructive interference and the creation of additional bound modes explain these behaviors. Therefore, the thickness of the anode buffer layers should be optimized under the upper limit, which creates additional bound modes. [ABSTRACT FROM PUBLISHER]