Quantitative Analysis of X-ray Lithographic Pores by SEM Image Processing

Arrays of regular macropores in electronic, magnetic, photonic and sensing devices can be patterned by X-ray lithography. Such structures inevitably contain some irregularity and require time-consuming pattern inspections. In this work, a pattern inspection by intensity-based digital image processing procedure is proposed and tested on scanning electron microscopy images of porous SU-8 polymer resist. The Otsu’s thresholding converted grayscale to binary images and the closing morphology algorithm was applied to reduce noise in the images. The Canny edge detector was used to identify the contour of each pore by detecting abrupt intensity changes in the binary image. Pores were detected and their sizes were subsequently evaluated. The morphological distributions analyzed by this procedure are comparable to those carried out by the one-by-one human inspection.     

Theoretical study of α-fluorenyl oligothiophenes as color tunable emissive materials for highly efficient electroluminescent device

The modifications of α-fluorenyl oligothiophenes by adding carbazole and pyrene end-capped moieties have been carried out using density functional theory (DFT) and time-dependent DFT (TD-DFT) method. The ground state conformation, energy gap, absorption, and emission properties as well as the change of λ_abs when oligothiophenes were increased up to 4 units have been investigated. We have fine-tuned the energy level and emission color by adjusting the conjugation length of the thiophene units connected to fluorene moieties. The results are pointed out that the excitation energies obtained by TD-DFT were decreased when the conjugation length was extended which strongly correspond to experimental observations, OLED devices of these materials emitted brightly in various colors from deep blue to orange with good color qualities and luminance efficiencies.