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A novel method for the fabrication of ink-jet-printed organic light-emitting-diode devices is discussed. Unlike previously reported solution-processed OLED devices, the emissive layer of OLED devices reported here does not contain polymeric materials. The emission of the ink-jet-printed P 2 OLED (IJ-P 2 OLED) device is demonstrated for the first ti...
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Context 1
... structure and fabrication of ink- jet-printed P 2 OLEDs Figure 2 shows the basic device structure of solution-proc- essed P 2 OLEDs. The sequence of organic layers in P 2 OLED devices constructed on ITO glass substrate is HIL/HTL/EML/BL/ ETL/LiF/Al. ...
Context 2
... in the solution-processed phosphorescent-OLED performance by spin-coating RGB P 2 OLEDs discussed in this paper are bottom-emitting devices fabricated on glass substrates. P 2 OLEDs fabricated by spin-coating have the same device structure as shown in Fig. 2. High-quality films were achieved by using spin- coated HIL, HTL, and EML. Figure 9 shows the normalized EL spectra of the red, green, and the newly developed sky-blue P 2 OLEDs meas- ured at 10 mA/cm 2 and the 1931 Commission International de l'Eclairage (CIE) ...
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Production of substrate for organic electronics – Reel to reel Vacuum metallization – organic vapour deposition production of TFTs, OLED, organic photovoltaic's – Micro and nanofabrication techniques – thermal imaging – Printing – Digital lithography for TFT fabrication – solution based printing.
Citations
... 8 In addition, it is also expensive to fabricate large-area pixels given the size of the evaporator. 9 However, the solutionprocessed fabrication of OLEDs such as using ink-jet printing technology could address the underlying limitations of the vacuum-sublimation technique. 10 In this context, using LC molecules consisting of peripheral alkyl chains not only makes them easily solution-processable but also allows for fine-tuning of their central chromophoric part which could serve as a source of pure deep-blue light emission in OLEDs. ...
... There are specific requirements for inks during the inkjet printing process, such as surface tension [181,182], viscosity [183], solvent density [184], and solvent evaporation rate [185,186], etc. Polymers with high molecular weights and amorphous characteristics have been regarded as the suitable choice of materials for inkjet printing [187][188][189], whereas inkjet printing of small molecules is advantageous in achieving high performance required for practical applications because of their well-defined structures, high chemical purity, and controllable reproducibility with no batch-to-batch variations [190][191][192]. However, commercial OLED small molecules generally show limited solubility and poor film morphologies via solution processing [6,193]. ...
This chapter deals with the fabrication of organic light‐emitting diode (OLED) devices based on solution‐processable materials. Before OLED fabrication, a correct choice of optimum device components is required, focusing on organic semiconductor optoelectronic properties as well as on electrode and carrier injection layer characteristics. Therefore, the material properties, as individuals or as blends, are initially discussed. These properties will lead to custom‐made OLEDs as a consequence of tuning and tailoring of the organic semiconductor properties and of the device preparation process. Rigid and flexible OLED devices are thereafter produced and characterized in terms of their operational properties and performance.
... There are two approaches to fabricate organic devices based on the materials employed: thermal vapor deposition and solution-based process. Spin coating or inkjet printing of polymers has been well studied since 1990 [40], and screen printing can efficiently be used to fabricate large area, high-resolution full-color flat panel displays [41,42]. ...
Semiconductor technologies that drive electronic appliances and devices such as TV displays, computers, tablets, and cell phones have been evolving rapidly. The pursuit of lightweight, thinner, high image resolution, energy-saving displays, and devices have encouraged scientists around the world to find new materials and its combinations to follow-up with those needs. In this respect, organic semiconductors have been extensively studied in the last two decades because of their versatility, low processing requirements, flexibility, and environment-friendly characteristics. Unlike inorganic materials, organic semiconductors do not exhibit a periodic atomic arrangement, and charge transport occurs along their carbon backbones with conjugated bonds. In this chapter, the structural characteristics, classification, conduction phenomena, and optical properties of polymers and small molecules are presented. Organic photovoltaic devices, thin-film transistors, and organic light-emitting diodes are the most common application of these materials, and their most important features are explained. A concise summary of the most commonly used vapor and solution processing techniques for organic semiconductor deposition is presented.
... Recently solution-processed small molecular organic light-emitting diodes (SMOLEDs) have attracted more attention because of the simple film forming process and good performance of devices [18][19][20]. Printable phosphorescent organic light-emitting devices have been demonstrated to be able to exhibit high performance and long lifetime [21,22]. ...
... On the other hand, the dewetting velocity of ink-jet printed liquid films is affected by the properties of the solvents. Solutions contained small molecular materials, in which there is not any inter-chain entanglement as polymers, belong to Newtonian fluids and can retain their initial viscosity as the solvents [21]. Eq. (1) shows the dewetting velocity of the ideal Newtonian fluids [39,40]: ...
Small molecular organic light-emitting diodes (SMOLEDs) were fabricated with an ink-jet printed film of 2-(t-butyl)-9,10-bis (20-naphthyl) anthracene (TBADN) doped with 4,4′-bis[2-{4-(N,N-diphenylamino)phenyl vinyl] (DPAVBi) as emitting layer. Dewetting behavior of ink-jet printed TBADN/DPAVBi solutions were restrained by adding cyclohexylbenzene or α-chloronaphthalene to the main solvent chlorobenzene. The high boiling point and high viscosity of cyclohexylbenzene and α-chloronaphthalene has increased the thickness of liquid films and the viscosity, which restrained the dewetting from thermodynamics and kinetics aspect. Uniform TBADN/DPAVBi films obtained by ink-jet printing from chlorobenzene/cyclohexylbenzene solution have been used in the fabrication of matrix display of SMOLEDs. The OLEDs has a turn-on voltage of 5.5V, the maximum luminance of 289cd/m2 and the maximum current efficiency of 0.71cd/A.
Inkjet printing is considered to be the most promising means of pixelated, large-scale processing of organic light-emitting diode (OLED) panels. However, the uniformity of printed films in the bank and...
Despite the huge successes of the organic light-emitting diodes (OLEDs) business by the thermal evaporation technology, the solution-process manufacturing technology offered an alternative way to construct low-cost and large-area OLED panels. Among all the solution-process technologies for OLEDs, inkjet printing (IJP) is particularly deemed as an interesting scalable and cost-effective way to construct large-area display panels, promising to be superior for its direct formation of red-green-blue side-by-side pixelated architecture. Compared with vacuum thermal evaporation (VTE)-based complex multilayered stacking device architecture of OLED, IJP-OLED employs a simpler device configuration and recently has been catching up in terms of device efficiency and lifetime. Therefore, it is of significance to fabricate highly stable and efficient IJP-OLEDs, which mainly rely on the materials and IJP fabrication processes. In this chapter, we will briefly introduce the current IJP technology for OLEDs and its fundamentals; developments of IJP-OLEDs based on fluorescent, phosphorescent, and thermal-activated delayed fluorescent emitting materials and industrial research progress of IJP-OLED.
Short‐circuit defects caused by microscale dust particles in organic light‐emitting diodes (OLEDs) cause a decrease in production yield and hinder cost reduction. An organic layer coating by solution process is used to prevent short‐circuit defects of particles on a substrate. In this study, the coverage properties of a coated organic layer on size‐controlled particles are revealed. The surface of the substrate with size‐controlled SiO2 particles with a diameter of 0.2–5 µm is quantitatively contaminated, and the particle coverage properties of the solution‐processed hole injection layer are investigated. From the results of the leakage current measurement and cross‐sectional observation by a transmission electron microscope, it is observed that devices with 50 nm‐spin‐coated poly (3,4‐ethylenedioxythiophene): poly(styrene sulfonate) can cover SiO2 particles up to 1 µm in diameter without any increase in leakage current. It is revealed that larger‐sized particles cause electric defects, albeit with a low probability, owing to the larger space under the particles. To fabricate OLEDs with a high yield, the shape of the coverage at the bottom of the particle is important in preventing electric defects. The results of this study are useful not only for OLEDs but also for printed and coated devices. To prevent short‐circuit defects caused by dust particles on substrates, the particle coverage properties of the spin‐coated hole injection layer are reported. Quantitatively contaminating the substrate surface with size‐controlled SiO2 particles, poly(3,4‐ethylenedioxy‐thiophene):poly(styrene sulfonate) is spin‐coated, resulting in coverage up to SiO2 particles 10–20 times larger than the film thickness.
Recently, there has been increasing interest in electrochemical printed sensors for a wide range of applications such as biomedical, pharmaceutical, food safety, and environmental fields. A major challenge is to obtain selective, sensitive, and reliable sensing platforms that can meet the stringent performance requirements of these application areas. Two-dimensional (2D) nanomaterials advances have accelerated the performance of electrochemical sensors towards more practical approaches. This review discusses the recent development of electrochemical printed sensors, with emphasis on the integration of non-carbon 2D materials as sensing platforms. A brief introduction to printed electrochemical sensors and electrochemical technique analysis are presented in the first section of this review. Subsequently, sensor surface functionalization and modification techniques including drop-casting, electrodeposition, and printing of functional ink are discussed. In the next section, we review recent insights into novel fabrication methodologies, electrochemical techniques, and sensors’ performances of the most used transition metal dichalcogenides materials (such as MoS2, MoSe2, and WS2), MXenes, and hexagonal boron-nitride (hBN). Finally, the challenges that are faced by electrochemical printed sensors are highlighted in the conclusion. This review is not only useful to provide insights for researchers that are currently working in the related area, but also instructive to the ones new to this field.
High‐performance solution‐processable light‐emitting diodes (LEDs) attract much research interest due to the very high complexity of conventional vacuum‐processed LEDs. A simple single‐inkjet‐printing process using a phase‐separable material combination is presented. With single‐inkjet printing of an ink containing semiconducting compounds on a phase‐separable insulating layer, convective and Marangoni flows in sessile droplets can produce microinlaid spots through the site‐selective etching of the insulating layer and the simultaneous self‐filling of the semiconductors in the etched vacancies. As a proof of concept, microinlaid organic LEDs (OLEDs) with a spatial resolution of ≈200 dpi in a phase‐separable poly(4‐vinylpyridine) layer without any conventional preformation of bank‐like structures are produced. The fabricated green microinlaid OLEDs exhibit excellent performance with maximum brightness of ≈13 000 cd m−2 and maximum efficiency of ≈14.2 cd A−1. Moreover, large‐area inkjet‐printed OLEDs are simply realized using the microinlaid spot arrays. These results demonstrate that the inkjet‐inlay structure is a promising candidate for high‐performance next‐generation solution‐processable LEDs. A light‐emitting inkjet‐inlaid spot is produced utilizing an appropriate material combination of a phase‐separable insulating polymer and functional semiconducting compounds for the simple and reliable fabrication of high‐performance small‐molecular micro‐organic light‐emitting diode (OLED) pixel arrays. Due to the self‐creation of high‐quality microinlaid spots, bright, efficient, and large‐area micro‐OLED pixel arrays are easily realized without any misalignment by the single‐inkjet‐printing process.
Development of materials that serve as efficient blue emitters in solution-processable OLEDs is challenging. In this study, we report three derivatives of C3-symmetric 1,3,5-tris(thien-2-yl)benzene-based highly luminescent room temperature columnar discotic liquid crystals (DLCs) suitable as solid-state emitters in OLED devices. When employed in solution-processed OLEDs, one of the derivatives having the highest photoluminescence quantum yield exhibited a maximum EQE of 4.7% and CIE chromaticity of (0.16, 0.05) corresponding to the ultra deep-blue emission. The finding is sufficiently significant in the field of DLC-based deep blue emitters.
