Built‐In Haze Glass‐Fabric Reinforced Siloxane Hybrid Film for Efficient Organic Light‐Emitting Diodes (OLEDs)

Abstract

Substrates with high transmittance and high haze are desired for increasing the light outcoupling efficiency of organic light‐emitting diodes (OLEDs). However, most of the polymer films used as substrate have high transmittance and low haze. Herein, a facile route to fabricate a built‐in haze glass‐fabric reinforced siloxane hybrid (GFRH) film having high total transmittance (≈89%) and high haze (≈89%) is reported using the scattering effect induced by refractive index contrast between the glass fabric and the siloxane hybrid (hybrimer). The hybrimer exhibiting large refractive index contrast with the glass fabric is synthesized by removing the phenyl substituents. Besides its optical properties, the hazy GFRH films exhibit smooth surface (Rsq = 0.2 nm), low thermal expansion (13 ppm °C−1), high chemical stability, and dimensional stability. Owing to the outstanding properties of the GFRH film, OLED is successfully fabricated onto the film exhibiting 74% external quantum efficiency enhancement. The hazy GFRH's unique optical properties, excellent thermal stability, outstanding dimensional stability, and the ability to perform as a transparent electrode enable them as a wide ranging substrate for the flexible optoelectronic devices.

Controlling Neutral Plane of Flexible Substrates by Asymmetric Impregnation of Glass Fabric for Protecting Brittle Films on Foldable Electronics

“…The neutral plane is linearly shifted from the center as the glass fabric is moved, implying that asymmetric impregnation of the glass fabric could be required to reduce the maximum tensile strain under bending. This is opposed to the symmetric structure of the conventional glass fabric–reinforced substrate [ 22–26 ] (see Figure S1, Supporting Information, for a detailed calculation procedure for the neutral plane shift).…”

“…Figure a shows the fabrication process of the 80 μm thick GFRH substrate with a controlled neutral plane (GFRH‐CNP). Glass fabric was used for neutral plane control, and a transparent ESH [ 25,26 ] was used to match the refractive index with the glass fabric for high transparency of the fabricated substrate. First, (i) ESH resin was impregnated on the glass fabric, and then (ii) roll lamination and pre‐UV curing were conducted to fix the glass fabric position.…”

“…This is in contrast to the conventional glass fabric–reinforced substrate of symmetric structure along the thickness, which has the neutral plane at the center of the substrate. [ 22–26 ] Consequently, the maximum tensile strain of the newly developed substrate under bending was reduced by a controlled neutral plane. To prove a controlled neutral plane of the developed substrate, a conventional colorless polyimide (CPI) substrate without a controlled neutral plane was simultaneously compared.…”

Inside or outside: Evaluation of the efficiency enhancement of OLEDs with applied external scattering layers

“…While the internal structures can result in high efficiency improvement, a careful implementation must be done to ensure electrical stability of the OLEDs. Another possibility is to directly embed scattering structures in the substrate 15–18 .…”

Investigation of the change of the shrinkage properties in contradiction to the change of the composition of cotton polyester spandex denim fabrics

“…Lim et al 17 reported that while processing the fabrics at wet zone from pretreatment to finishing, the problem of shrinkage may be occurred due to uneven tension either by the mercerizing operation or by the stenter chain.…”