Browsing by Author "Yeh, Yu-Shan"

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Color tuning associated with heteroleptic cyclometalated Ir(III) complexes: influence of the ancillary ligand
(2007)
Chang, Chau-Jiun
;
Yang, Cheng-Han
;
Chen, Kellen
;
Chi, Yun
;
Shu, Ching-Fong
We report the preparation of a series of new heteroleptic Ir(III) metal complexes chelated by two cyclometalated 1-(2,4-difluorophenyl) pyrazole ligands (dfpz)H and a third ancillary bidentate ligand ( L. X). Such an intricate design lies in a core concept that the cyclometalated dfpz ligands always warrant a greater pi pi* gap in these series of iridium complexes. Accordingly, the lowest one-electron excitation would accommodate the pi* orbital of the ancillary L(boolean AND)X ligands, the functionalization of which is then exploited to fine-tune the phosphorescent emission wavelengths. Amongst the L. X ligands designed, three classes (series 1-3) can be categorized, and remarkable bathochromic shifts of phosphorescence were observed by (i) replacing the 2-benzoxazol-2-yl-substituent (1a) with the 2-benzothiazol-2-yl group (1b) in the phenolate complexes, (ii) converting the pyridyl group (2a) to the pyrazolyl group (2b) and even to the isoquinolyl group (2c) in the pyrazolate complexes and (iii) extending the pi-conjugation of the benzimidazolate ligand from 3a to 3b. Single-crystal X-ray diffraction study on complex [(dfpz)Ir(bzpz)] (2b) was conducted to confirm their general molecular architectures. Complex 2b was also used as a representative example for fabrication of multilayered, green-emitting phosphorescent OLEDs using the direct thermal evaporation technique.
Pore size evaluation of mesoporous organosilicate films by non-destructive X-ray reflectivity methods
(2015-06-01)
Chien, Yun-San
;
Yeh, Yu-Shan
;
Chen, Yen-Song
;
Leu, Jih-Perng
;
Fu, Wei-En
200-nm-thick organosilicate films deposited by mixture of tetraethyl orthosilicate (TEOS) and methyltrimethoxysilane (MTMS) dissolving in different cetrimonium bromide (CTAB)/ethanol ratios were characterized in terms of pore size determination and its distribution. Under the toluene ambient, the pores would adsorb the gas hence elevating the whole film density. The X-ray reflectivity (XRR) equipped with mass flow control was utilized to detect the film density increasing. By fitting with Gaussian function and conversing with Kelvin\'s equation, the pore size was increased from 6.2 to 10.8 angstrom as the CTAB/ethanol ratio increasing to 0.075. It was attributed to the ethanol and CTAB enhanced the TEOS hollow droplets stability and dissolvability. As the CTAB/ethanol ratio is further increased, the pore size is reversely decreased, owing to the formation of solid microspheres. The non-destructive XRR measurement can evaluate the sub-nano pore sizes and its size distribution, which would fascinate the development and characterization of back-end of line process. (C) 2015 The Japan Society of Applied Physics