Dynamic Change in Color Filter Layers during the Baking Process by Multi‐Speckle Diffusing Wave Spectroscopy

Abstract

Undercut defects of color filter (CF) layers, which inevitably occur in UV curing and development processes for liquid crystal displays and white organic light‐emitting diodes, should be elucidated to ensure product quality and processability. The dynamic changes of the green CF layer are investigated during the baking process by examining the motion of pigment particles within the thin CF layer via multi‐speckle diffusing wave spectroscopy (MSDWS). Autocorrelation functions and characteristic times for the α‐relaxation, which are determined using light intensities scattered from the CF layer, directly indicate thermal melting and curing stages in the process. It is confirmed that MSDWS is a reliable non‐contact measurement tool for quantitatively analyzing the initial change of the CF layer during the baking process.

Light-Scattering Analysis of Drying Behavior in Suspension Droplets with Silica and Polystyrene Particles and a Hydrosoluble Polymer

“…In silica suspensions, the height ratio, defined as the edge height divided by the center height of droplet, decreased from 20.96 for S5 to 7.70 for S5C09, whereas its ratio increased from 3.57 for PS5 to 19.54 for PS5C09. To clarify the suppression or enhancement of the coffee-ring effect by the addition of a small amount of HEC, the drying dynamics of silica and PS suspensions with and without HEC were investigated using MSDWS for 1 μL suspension droplets to capture the drying behavior of the entire droplet (Figure ), as in previous studies. ,− The addition of HEC caused significantly retarded autocorrelation functions of S5C09 compared to those of S5, which was ascribed to the reduced mobility of HEC-adsorbed silica particles. Therefore, the particles were less affected by the outward capillary flow, which effectively suppressed the coffee-ring effect.…”

“…Typically, DWS is used to evaluate short-term self-diffusivity by analyzing the mean square displacement (MSD) in the ergodic state or viscoelastic properties of dense suspensions across a wide range of frequencies. , The MSD data obtained through DWS, which operates within the time scale of Brownian motion, can be employed to estimate particle migration only at the initial drying stage, which is mainly influenced by the Brownian motion of particles, considering negligible evaporation of solvent . MSDWS is an attractive tool for evaluating particle mobility in nonergodic states that cannot be detected by DWS. − The ensemble-averaged scattering intensities collected by multiple detectors at specific time points during the drying process provide valuable information regarding the movement of particles within the suspension system. , Thus, in addition to assessing particle mobility through DWS before the drying stage, MSDWS can be used for the real-time analysis of the fast dynamics (referred to as β-relaxation behavior) of colloidal particles, while particulate suspensions evaporate.…”

“…28−30 The ensemble-averaged scattering intensities collected by multiple detectors at specific time points during the drying process provide valuable information regarding the movement of particles within the suspension system. 31,32 Thus, in addition to assessing particle mobility through DWS before the drying stage, MSDWS can be used for the real-time analysis of the fast dynamics (referred to as β-relaxation behavior) of colloidal particles, while particulate suspensions evaporate.…”

“…Furthermore, the local mobilities of the particles in the central and peripheral regions of the suspension droplets during drying were compared. In contrast to our previous studies, which mainly focused on the average particle motion throughout the entire droplet, ,− this approach adopts a different perspective. To facilitate a more pertinent analysis of the drying dynamics at local levels, at both the center and edge positions, we conducted a series of observations using a larger droplet volume compared to that used in previous studies.…”

Improvement of the photopolymerization and bottom-curing performance of benzocarbazole oxime ester photoinitiators with red-shifted absorption

“…[10][11][12] Recent increase in the resolution of the display in these years, however, leads to the decrease in the pixel size, which induces several problems in the manufacturing processes. The decrease in the size also decreases the contact area of the manufactured pattern on the glass substrate, [13][14][15][16] resulting in easy peeling due to the small adhesive strength. In addition, blue and black resists usually have strong absorption bands in the UV region.…”