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.
From the very first time that graphene was used as a transparent electrode for OLED applications, the emergence of active-matrix (AM)-graphene OLED displays has been envisioned. Realizing this expectation, however, turned out to be difficult. Two obstacles are the growth and transfer of a large-area graphene film and the patterning of a graphene film into pixels. To solve these problems, a process of patterning a graphene film without surface contamination was developed. The fabrication of OLED panels by the patterned graphene anode on Gen 2(370 × 470 mm)-sized and flexible substrates was successfully demonstrated. In this work, oxide TFT arrays were combined as a switching backplane, and a pixelated graphene OLED was used as an emissive layer, to realize AM-graphene OLED displays. To explore the technical feasibility of flexible AM-graphene OLED displays, the aforementioned components were formed on a flexible substrate. For commercial-level production, all the processes that were used were chosen to be compatible with the conventional display processes.
This work extends the kinds of organic materials that can form nano-lens arrays (NLAs). We have previously addressed fabrication of a N,N′-di(1naphthyl)-N,N′-diphenyl-(1,1′-biphenyl)-4,4′-diamine (NPB) NLA and explained the formation mechanism as NPB crystallization and the resulting increase in surface tension. Here, we report a Tris(8-hydroxyquinolinato)aluminum (Alq 3 ) NLA fabricated by the same deposition method as a NPB NLA. Grazing-incidence small-angle X-ray scattering experiments indicate that the formation mechanism of the Alq 3 NLA is the same as that of the NPB NLA. Furthermore, this study broadens the application of NLAs from rigid to flexible organic light-emitting diodes (OLEDs). Here, flexible stainless steel-based devices using a low-temperature thermal release film, atomic layer deposition and NPB NLA processes are fabricated and characterized. With a NLA, current efficiency is increased 1.4 times, indicating that fab-compatible NLA technology is also available for flexible OLEDs.
We report the use of broadband and high‐power InGaAs/GaAs asymmetric double quantum‐well (ADQW) superluminescent diodes (SLDs), which consist of a tilted, bent, and straight waveguide. To examine the effects of the arrangement of the ADQW and the gain provided by a straight waveguide on the output performances, we fabricated SLDs with different lengths for two types of ADQW, that is, a wide QW at the p‐side for Sample 1, and a narrow QW at the p‐side for Sample 2, and tested their spectral width and output power. The fabricated SLDs with a straight length (L3) of 80 μm show −3 dB spectral widths of 122 and 116 nm and output powers of 20 and 16 mW at an injection current of 250 mA for Samples 1 and 2, respectively. For both samples, it appears that, as the L3 increases, the spectral width decreases and the output power increases. From this result, we confirmed that both the spectral width and the output power can be adjusted and optimized at a given structure for various applications.
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