Browsing by Author "Chen, Wei-Chi"

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Morphological study of P3HT:PCBM blend films prepared through solvent annealing for solar cell applications
(2010-12-01)
Chen, Fang-Chung
;
Ko, Chu-Jung
;
Wu, Jyh-Lih
;
Chen, Wei-Chi
;
光電工程學系
We have systematically investigated the morphology of poly(3-hexylthiophene: P3HT) and [6,6]-phenyl C(61)-butyic acid methyl ester (PCBM) blend films prepared through a slow growth apparoch as a function of PCBM loading in the blends for bulk heterojunction solar cells. In addition to the electrical characterisitcs, the molecular ordering and crystallinity of the polymers was examined by using the UV-vis spectroscopy and grazing incidence X-ray diffraction. From the images of confocal laser scan microscopy, we were also able to in-situ monitor the phase separation of the P3HT:PCBM blends during the process of solvent evaporation. Finally, the conductive atomic force microscopy was utilized to probe the spatial distribution of the local current across the photoactive layer prepared with various P3HT:PCBM ratios. From the experimental results, we found that the distribution of PCBM molecules in the P3HT matrix became homogeneous after the solvent annealing process, even though the distribution of the PCBM molecules was not even in the beginning. Therefore, the higher device efficiency could be attributed to the better thin-film morphology of the polymer blends. (C) 2010 Elsevier B.V. All rights reserved.
Stacked Structures for Assembling Multiple Organic Photovoltaic Devices
(2012-07-01)
Chen, Wei-Chi
;
Chien, Shang-Chieh
;
Chen, Fang-Chung
;
Hsu, Chain-Shu
;
應用化學系
We have prepared semitransparent organic photovoltaic devices for constructing stacked structures. Through the study of the thickness effect of the photoactive layer, we found that sophisticated optimization of device matching was not required for achieving high performance while the subcells were connected in parallel. The results suggest that the stacked structure might be able to provide the other approach for assembling multiple devices while current matching between the subcells cannot be easily obtained. (c) 2012 The Japan Society of Applied Physics