Photophysical Properties of Hydroxylated Amphiphilic Poly(p-phenylene)s
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- 作者：Renu Ravindranath ; Chellappan Vijila ; Parayil Kumaran Ajikumar ; Fathima Shahitha Jahir Hussain ; Kong Li Ng ; Hezhou Wang ; Chua Soo Jin ; Wolfgang Knoll ; Suresh Valiyaveettil
- 刊名：Journal of Physical Chemistry B
- 出版年：2006
- 出版时间：December 28, 2006
- 年：2006
- 卷：110
- 期：51
- 页码：25958 - 25963
- 全文大小：288K
- 年卷期：v.110,no.51(December 28, 2006)
- ISSN：1520-5207
文摘
A homologous series of polyhydroxylated poly(p-phenylene)s with different alkoxy groups (C6PPPOH, C12PPPOH, and C18PPPOH) were synthesized with use of the Suzuki polycondensation reaction. Comparativestudies of the structure correlation between their photophysical properties and film morphology is described.The absorption and emission spectra of polymers in solution and thin films showed similar features indicatingthat the electronic properties in solution were retained in the film state. Compared to the polymer with theshort alkoxy chains (C6PPPOH), the polymers with long alkoxy groups (C12PPPOH and C18PPPOH) showedimproved film forming properties with continuous and smooth film morphology. The absorption propertiesof the C12PPPOH showed an enhanced effective conjugation length and high quantum yield implyingplanarization of the backbone through alkoxy chain packing (C12H25O-) and potential hydrogen bonds. Nooverlap in the absorption and emission spectra was observed, which indicated minimized excimer formationor excitation energy transfer in the films. Time-resolved fluorescence measurements showed that the decaytimes increased from 43 ps (C6PPPOH) to 78 ps (C12PPPOH) and 99 ps (C18PPPOH). Electrochemical studieswere performed for all polymers and the observed oxidation potential for C6PPPOH was higher than that ofC12PPPOH and C18PPPOH. In addition, the C12PPPOH has the lowest band gap of 
E = 2.59 eV whencompared to the 3.1 (C6PPPOH) and 2.61 eV (C18PPPOH) gaps. The optical band gaps estimated from theabsorption onset of the polymers are significantly higher than those obtained from electrochemical data. C12PPPOH was chosen for investigating the charge carrier mobility by the time-of-flight (TOF) technique. Theobserved results also showed negative field dependent values of the drift mobility for the polymer C12PPPOH.
E = 2.59 eV whencompared to the 3.1 (C6PPPOH) and 2.61 eV (C18PPPOH) gaps. The optical band gaps estimated from theabsorption onset of the polymers are significantly higher than those obtained from electrochemical data. C12PPPOH was chosen for investigating the charge carrier mobility by the time-of-flight (TOF) technique. Theobserved results also showed negative field dependent values of the drift mobility for the polymer C12PPPOH.