Ink viscosity detection
01 Introduction to Quantum Dots Quantum dots (QD), also known as semiconductor nanocrystals, are a class of II-VI elements (such as CdS, CdSe, CdTe, ZnSe, ZnS, etc.) or III-V elements (cadmium-free quantum). The size of a semiconductor material such as InP, InAs, etc.). Nanoparticles between 1-10 nm. Quantum dots have excellent characteristics such as high color purity, high luminescence quantum efficiency, adjustable luminescent color, and long service life. These characteristics make quantum dot light-emitting diodes (QLEDs) using quantum dot materials as light-emitting layers have broad application prospects in the fields of solid-state illumination and flat panel display, and have attracted extensive attention from academia and industry.
02 The significance of quantum dot ink viscosity measurement Compared with traditional organic light-emitting diode display devices, QLED has the advantages of narrow emission peak, high color saturation and wide color gamut. Front QLED
Solutions for achieving pixelation and full coloring include a transfer method, a micro-contact printing method, a knife coating method, a jet printing method, and an inkjet printing method. Compared with the previous methods, the inkjet printing technology can accurately deposit the quantum dot luminescent material in the proper amount to make the semiconductor material uniformly deposited to form a thin film layer, thereby making the material utilization rate very high, and the manufacturer. It can reduce production costs, simplify the production process, and facilitate mass production and popularization of products. The key to inkjet printing technology is the preparation of quantum dot ink. The viscosity of ink directly affects the inkjet process and the film drying process. It is an important parameter to measure the inkjet printing effect.
Quantum dot inks are usually dispersed in organic reagents by quantum dot materials. Since the quantum dot materials themselves are nanoparticles, it is difficult to obtain high-viscosity inks. The viscosity of the inks is too low, making ink droplets difficult to control during printing, and easy to appear comet points. The problem is that the edge of the thick thin intermediate coffee ring causes the quantum dot film thickness to be inconsistent and the uniformity is poor. A large number of studies have shown that in the preparation process of quantum dot inks, the viscosity modifier, initiator and other additives can be appropriately added to optimize the viscosity of the ink by optimizing the solvent formulation and ratio, and the ink is too low in viscosity. The above problem of inkjet printing. It can meet the requirements of inkjet printing process, and achieve the technical requirements of stable ink discharge, stable spreading, uniform drying, and uniform film formation.
03 Quantum dot ink viscosity determination This article uses a DV2T cone and plate viscometer + TC-650 AP circulating water bath system (shown in Figure 1) to test the viscosity of a quantum dot ink (user supplied) at 25 °C. The TC-650AP water bath cycle system is used to control the sample temperature. The Rheocalc T software is connected to the main unit for program editing and data acquisition to plot the viscosity change curve. Adjust the gap between the rotor of the cone and plate viscometer and the sample cup according to the viscometer operation manual, and then draw a certain amount of quantum dot ink into the sample cup of the cone and plate viscometer. After the rotor and the sample cup are installed, connect the viscometer. Host and water bath circulation system, set the test temperature to 25 °C. The viscosity test procedure was edited using the Rheocalc T software and the viscosity test was started after the sample temperature stabilized. According to the results of Figure 2, we can see.
01 Introduction to Quantum Dots Quantum dots (QD), also known as semiconductor nanocrystals, are a class of II-VI elements (such as CdS, CdSe, CdTe, ZnSe, ZnS, etc.) or III-V elements (cadmium-free quantum). The size of a semiconductor material such as InP, InAs, etc.). Nanoparticles between 1-10 nm. Quantum dots have excellent characteristics such as high color purity, high luminescence quantum efficiency, adjustable luminescent color, and long service life. These characteristics make quantum dot light-emitting diodes (QLEDs) using quantum dot materials as light-emitting layers have broad application prospects in the fields of solid-state illumination and flat panel display, and have attracted extensive attention from academia and industry.
02 The significance of quantum dot ink viscosity measurement Compared with traditional organic light-emitting diode display devices, QLED has the advantages of narrow emission peak, high color saturation and wide color gamut. Front QLED
Solutions for achieving pixelation and full coloring include a transfer method, a micro-contact printing method, a knife coating method, a jet printing method, and an inkjet printing method. Compared with the previous methods, the inkjet printing technology can accurately deposit the quantum dot luminescent material in the proper amount to make the semiconductor material uniformly deposited to form a thin film layer, thereby making the material utilization rate very high, and the manufacturer. It can reduce production costs, simplify the production process, and facilitate mass production and popularization of products. The key to inkjet printing technology is the preparation of quantum dot ink. The viscosity of ink directly affects the inkjet process and the film drying process. It is an important parameter to measure the inkjet printing effect.
Quantum dot inks are usually dispersed in organic reagents by quantum dot materials. Since the quantum dot materials themselves are nanoparticles, it is difficult to obtain high-viscosity inks. The viscosity of the inks is too low, making ink droplets difficult to control during printing, and easy to appear comet points. The problem is that the edge of the thick thin intermediate coffee ring causes the quantum dot film thickness to be inconsistent and the uniformity is poor. A large number of studies have shown that in the preparation process of quantum dot inks, the viscosity modifier, initiator and other additives can be appropriately added to optimize the viscosity of the ink by optimizing the solvent formulation and ratio, and the ink is too low in viscosity. The above problem of inkjet printing. It can meet the requirements of inkjet printing process, and achieve the technical requirements of stable ink discharge, stable spreading, uniform drying, and uniform film formation.
03 Quantum dot ink viscosity determination This article uses a DV2T cone and plate viscometer + TC-650 AP circulating water bath system (shown in Figure 1) to test the viscosity of a quantum dot ink (user supplied) at 25 °C. The TC-650AP water bath cycle system is used to control the sample temperature. The Rheocalc T software is connected to the main unit for program editing and data acquisition to plot the viscosity change curve. Adjust the gap between the rotor of the cone and plate viscometer and the sample cup according to the viscometer operation manual, and then draw a certain amount of quantum dot ink into the sample cup of the cone and plate viscometer. After the rotor and the sample cup are installed, connect the viscometer. Host and water bath circulation system, set the test temperature to 25 °C. The viscosity test procedure was edited using the Rheocalc T software and the viscosity test was started after the sample temperature stabilized. According to the results of Figure 2, we can see.
Using the “Multi Point†function to collect data, the “Test Averaging†function calculates the viscosity average, and observes and analyzes the instrument stability and data fluctuations during the test. According to Figure 2, the quantum dot ink is measured at a speed of 15 RPM. The viscosity value obtained was 10.18 cP; during the test, the data fluctuation was very small, and the relative standard deviation was only 0.04%. The Brookfield Digital Viscometer's unique continuous sensor ensures real-time and accurate test data output. In addition, the temperature was very stable during the test and was always maintained at 25 ± 0.01 °C. The sample volume required for the cone and plate viscometer test is only 0.5-2.0 mL (the specific sample size is related to the rotor type used), especially suitable for the viscosity test of a small sample, which can effectively reduce the consumption of the product; the cone and plate viscometer is used. The conical rotor and the matching sample cup can accurately calculate the shear rate and shear stress to obtain the absolute viscosity. Due to the small amount of sample, the rapid temperature can be achieved and the test efficiency can be effectively improved. The temperature control accuracy of the TC-650 AP circulating water bath system can reach 0.01 °C, providing accurate and stable temperature conditions for viscosity testing.
04 Application Overview As one of the world's leading manufacturers of viscometers/rheometers, Ametek-Brookfield is committed to providing customers with consistent quality, high measurement accuracy and good repeatability. The Brookfield viscometer measures up to ±1% of the full-scale measurement range with repeatability of ±0.2%. For individual viscosity testing needs, we offer a personalized solution that is perfectly adapted to the analytical needs of users in a variety of industries.
The RST rheometer offers comprehensive rheology testing for perfect rheological analysis in both quality control and R&D. The RST Series rheometers have two modes of controlling shear rate and shear stress, and are especially suitable for measuring the viscosity and rheological curves of non-Newtonian fluids under steady flow. In addition, it can measure rheological properties such as viscoelasticity, yield stress and thixotropic properties in unsteady shear flow and creep conditions.
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