Pulsed-laser micropatterned quantum-dot array for white light source

Wang, Shengwen; Lin, Hsiao‐Yi; Lin, Chin-Teng; Kao, Tsung Sheng; Chen, Kuo-Ju; Han, Hau-Vei; Li, Jie-Ru; Lee, Po-Tsung; Chen, Huang-Ming; Hong, Minghui; Kuo, Hao‐Chung

doi:10.1038/srep23563

Cited by 17 publications

(11 citation statements)

References 23 publications

(23 reference statements)

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“…Ink temperature instability, as well as solvent evaporation are noted as the leading causes of materialrelated fluctuations, such as ink predrying and particulate accumulation within the nozzle [17]. As mentioned earlier, depending on link viscosity, ultrasonic or pneumatic atomization can be used [12,18,[20][21][22][23][24][25][26][27]. For instance, Fig.…”

Section: Feasibility Of Online Monitoring In Ajp Processmentioning

confidence: 99%

“…The density of a line is defined as the average of the grayscale intensity values of all pixels located between the detected upper and lower edges (i.e., located within the line area) as mathematically shown by Eq. (26). In order to offset the effect of illumination on the intensity of the pixels (depending on experimental conditions, camera settings, etc.…”

Section: Line Density (L Q )mentioning

confidence: 99%

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Computational Fluid Dynamics Modeling and Online Monitoring of Aerosol Jet Printing Process

Salary

Lombardi

Tootooni

et al. 2016

Journal of Manufacturing Science and Engineering

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The objectives of this paper in the context of aerosol jet printing (AJP)—an additive manufacturing (AM) process—are to: (1) realize in situ online monitoring of print quality in terms of line/electronic trace morphology; and (2) explain the causal aerodynamic interactions that govern line morphology based on a two-dimensional computational fluid dynamics (2D-CFD) model. To realize these objectives, an Optomec AJ-300 aerosol jet printer was instrumented with a charge coupled device (CCD) camera mounted coaxial to the nozzle (perpendicular to the platen). Experiments were conducted by varying two process parameters, namely, sheath gas flow rate (ShGFR) and carrier gas flow rate (CGFR). The morphology of the deposited lines was captured from the online CCD images. Subsequently, using a novel digital image processing method proposed in this study, six line morphology attributes were quantified. The quantified line morphology attributes are: (1) line width, (2) line density, (3) line edge quality/smoothness, (4) overspray (OS), (5) line discontinuity, and (6) internal connectivity. The experimentally observed line morphology trends as a function of ShGFR and CGFR were verified with computational fluid dynamics (CFD) simulations. The image-based line morphology quantifiers proposed in this work can be used for online detection of incipient process drifts, while the CFD model is valuable to ascertain the appropriate corrective action to bring the process back in control in case of a drift.

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Section: Feasibility Of Online Monitoring In Ajp Processmentioning

confidence: 99%

Section: Line Density (L Q )mentioning

confidence: 99%

Computational Fluid Dynamics Modeling and Online Monitoring of Aerosol Jet Printing Process

Salary

Lombardi

Tootooni

et al. 2016

Journal of Manufacturing Science and Engineering

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“…While the ion migration issue is yet to be completely resolved for mixed Br/I perovskites, red LEDs were also achieved with this material set. The here is 30 % larger [230]. This proves that we have achieved a wide range of colour tuneability in these LEDs.…”

Section: Discussionsupporting

confidence: 64%

Nanostructured Inorganic Metal Halide Perovskites for Optoelectronic Applications

Vashishtha¹

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<p>Semiconductor quantumdots have proven to be promising materials for optoelectronic devices, such as light emitting devices (LEDs) and solar cells, due to their thin linewidth of emission, high photoluminescence quantum yield and high absorption coefficient. Over the last decade, perovskite crystals have gained significant attention due to their extraordinary optoelectronic properties. Therefore, perovskite nanocrystals combine the advantage of both crystalline perovskite and quantum dots. Here, we synthesised high quantum yield (50 - 80 %) monodispersed CsPbX₃ (X= Cl, Br, I) quantum dots, with tuneable emission spectra over the entire visible region, by a colloidal synthesis method. We have then successfully processed them to produce thin films as the emitting layer in an organic LED-type device architecture. Most importantly, we demonstrated field induced halide separation in mixed halide CsPb(Br/I)₃ NCs which is the reason color instability in these LEDs. Perovskite nanocrystal LEDs were found to have low external quantum efficiency (EQE) due to their bulky ligands. As a result, Ruddlesden-Popper (RP) phase layered perovskite was investigated to increase the EQE over perovskite QD LEDs. As a result, we constructed RP perovskite phase CsPbX₃ LEDs with emission through the entire visible spectrum (460-700 nm). Colour tuning was achieved by taking advantage of both quantum confinement effect and halide mixing. The EQE of these LEDs outperformed the literature values in the blue and blue-green spectral regions, with relatively long life time. We also invented a novel perovskite nanocrystals made from thalliumlead halide by replacing caesium with thallium. These materials are potential candidates for various optoelectronic applications. Size-, shape-, and composition- tuning in these nanocrystals were performed by varying the reaction conditions andmixing the halide composition. A weak confinementwas observed in these NCs. Additionally, we have shown the application of TlPbI₃ nanowires as photoconductors. Collectively, this thesis includes the synthesis of various types of inorganic metal halide perovskite nanostructures followed by their implementation into working optoelectronic devices, specifically LEDs.</p>

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“…1.1 Motivation and Significance. Aerosol jet printing (AJP) is a droplet-based direct-write additive manufacturing process, which has emerged as a high-resolution method for the fabrication of a broad spectrum of electronics, e.g., interconnects [1][2][3], optical waveguides [4,5], optoelectronic devices [6][7][8], organic light emitting diodes [8], quantum dot devices [9,10], fine-pitch electronics [11], sensors [12,13], and transistors [14][15][16]. AJP has a large stand-off distance, allowing for fine material deposition and device fabrication on nonplaner surfaces (with feature sizes as small as 10 lm) [17][18][19].…”

Section: Introductionmentioning

confidence: 99%

A Computational Fluid Dynamics Investigation of Pneumatic Atomization, Aerosol Transport, and Deposition in Aerosol Jet Printing Process

Salary

Lombardi

Weerawarne

et al. 2021

Journal of Micro and Nano-Manufacturing

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Aerosol jet printing (AJP) is a direct-write additive manufacturing technique, which has emerged as a high-resolution method for the fabrication of a broad spectrum of electronic devices. Despite the advantages and critical applications of AJP in the printed-electronics industry, the AJP process is intrinsically unstable, complex, and prone to unexpected gradual drifts, which adversely affect the morphology and consequently the functional performance of a printed electronic device. Therefore, in situ process monitoring and control in AJP is an inevitable need. In this respect, in addition to experimental characterization of the AJP process, physical models would be required to explain the underlying aerodynamic phenomena in AJP. The goal of this research work is to establish a physics-based computational platform for prediction of aerosol flow regimes and ultimately, physics-driven control of AJP process. In pursuit of this goal, the objective is to forward a 3D compressible, turbulent, multi-phase CFD model to investigate the aerodynamics behind: (i) aerosol generation, (ii) aerosol transport, and (iii) aerosol deposition on a moving free surface in the AJP process. The complex geometries of the deposition head as well as the pneumatic atomizer were modeled in the ANSYS-Fluent environment, based on patented designs and also accurate measurements, obtained from 3D X-ray computed tomography (CT) imaging. The entire volume of the constructed geometries was subsequently meshed, using a mixture of smooth and soft quadrilateral elements, with consideration of layers of inflation to obtain an accurate solution near the walls. A combined approach - based upon the density-based and pressure-based Navier-Stokes formation - was adopted to obtain steady-state solutions and to bring the conservation imbalances below a specified linearization tolerance (i.e., ?10?^(-6)). Turbulence was modeled, using the realizable k-? viscous model with scalable wall functions. A coupled two-phase flow model was, in addition, set up to track a large number of injected particles. The boundary conditions were defined based on experimental sensor data, recorded from the AJP setup. The accuracy of the model was validated using a factorial experiment, composed of AJ-deposition of silver nanoparticles on a polyimide substrate. The outcomes of this study pave the way for the implementation of physics-driven in situ control of AJP.

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Pulsed-laser micropatterned quantum-dot array for white light source

Cited by 17 publications

References 23 publications

Computational Fluid Dynamics Modeling and Online Monitoring of Aerosol Jet Printing Process

Computational Fluid Dynamics Modeling and Online Monitoring of Aerosol Jet Printing Process

Nanostructured Inorganic Metal Halide Perovskites for Optoelectronic Applications

A Computational Fluid Dynamics Investigation of Pneumatic Atomization, Aerosol Transport, and Deposition in Aerosol Jet Printing Process

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