Browsing by Author "Chiu, Kuan-Cheng"

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Effects of isomeric transformation on characteristics of Alq3 amorphous layers prepared by vacuum deposition at various substrate temperatures
(2007-06-15)
Jian, Zhi-An
;
Luo, Ying-Zi
;
Chung, Jia-Ming
;
Tang, Shiow-Jing
;
Kuo, Ming-Chin
Organic tris(8-hydroxyquinoline)aluminum (Alq3) amorphous layers are prepared by vacuum deposition at various substrate temperatures T-sub from 30 to 180 degrees C. The surface morphology and electrical characteristics of these as-deposited layers are studied by atomic force microscopy and current-density versus electric-field (J-E) curves. The temperature dependence of the dark electrical conductivity sigma(T) determined from J-E curves is also examined. These experimental results reveal that the surface and electrical properties of Alq3 amorphous layers deposited at T-sub between 90 and 120 degrees C exhibit an anomalous T-sub dependence. However, this anomalous T-sub dependence is not observed from infrared absorption measurements, and therefore is not the result of chemical degradation. The observed behavior is explained in terms of the property that the vacuum deposition of Alq3 with T-sub between 90 and 120 degrees C involves a thermal interconversion between meridional and facial Alq3 isomers. (c) x 2007 American Institute of Physics.
Effects of source and substrate temperatures on the properties of ITO/CuPc/C-60 heterostructure prepared by physical vapor deposition
(2008-04-01)
Chiu, Kuan-Cheng
;
Juey, Liu-Ting
;
Su, Chih-Feng
;
Tang, Shiow-Jing
;
Jong, Ming-Nan
Small-molecule organic photovoltaic (OPV) cells with a heterostructure of indium tin oxide (ITO)/copper phthalocyanine (CuPc)/C-60/Ag were fabricated by physical vapor deposition at different source temperatures T-sou and substrate temperatures T-sub. The physical properties of these as-deposited organic thin films including surface morphology, structural information, and electrical and optical properties were measured (in layer-by-layer sequence) by atomic force microscopy, X-ray diffraction, current-voltage characteristics, and electronic absorption spectra. At first, the effects of different deposition conditions (Tsou and Tsub) on growth rate and film thickness of these organic thin films were examined. Then, the interface properties of ITO/CuPc and CuPc/C-60 were studied with respect to T-sub. Short-circuit current density J(sc) and open-circuit voltage V c for this ITO/CuPc/C-60/Ag heterostructure under illumination were performed, and the spectral response of J(sc) was analyzed. Finally, the Tub-dependence of the physical properties of the as-deposited organic films and of the performance of the as-fabricated OPV cells were discussed. (c) 2007 Elsevier B.V. All rights reserved.