Structural evolution and its effect on optical absorption/emission behavior of derivatives of PFs upon heat treatment at different temperatures were studies by means of a combination of x-ray diffraction, transmission electron microscopy and molecular simulation.
The main physical characteristics from results of this study over a series of PFs with alkyl side-chains may be summarized as the following:
(1) The crystal structure of poly (9,9-di-n-octyl- 2,7-fluorene, PF8) and poly(9,9-bis(2- ethylhexyl)- 2,7-fluorene, PF26) are determined via a combination of selected area electron diffraction and molecular simulation. In PF8 case, there are 8 chains in an orthorhombic unit cell with dimensions a = 2.56 nm, b = 2.34 nm, c (chain axis) = 3.32 nm, space group P212121, and calculated density of 1.041 gcm-3. On the other hand, in PF26 case, there are 3 chains in a trigonal unit cell with dimensions a = 1.67 nm, b = 1.67 nm, c (chain axis) = 4.04 nm, space group P3, and calculated density of 0.991 gcm-3.
(2) All the simulation results indicate that branched side-chains in the case of PF26 tend to fill the space among backbones. In contrast, the linear side-chains in the case of PF8 appear to embrace the neighboring backbone, favoring formation of layered structure.
(3) As a consequence, co-planrity of PF backbones is decreased by the attached alkyl side-chains. This in turn results in lowered conjugation length, and in favor of blue light emission.
| Identifer | oai:union.ndltd.org:NSYSU/oai:NSYSU:etd-0728104-091655 |
| Date | 28 July 2004 |
| Creators | Chou, Hung-Lung |
| Contributors | M. Chen, R. M. Ho, P. D. Hong, J. L. Hong, H. L. Chen, A. C. Su |
| Publisher | NSYSU |
| Source Sets | NSYSU Electronic Thesis and Dissertation Archive |
| Language | English |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://etd.lib.nsysu.edu.tw/ETD-db/ETD-search/view_etd?URN=etd-0728104-091655 |
| Rights | unrestricted, Copyright information available at source archive |
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