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|Title: ||Theoretical investigation the electroluminescence characteristic of pyrene and its derivatives|
|Authors: ||王伯昌;Wang, Bo-cheng;Chang, Jian-chuang;Tso, Hsi-chun;Hsu, Hsiu-fu;Cheng, Chang-yuan|
|Issue Date: ||2009-12-01|
|Abstract: ||The chromophore of pyrene molecule has been studied in detail by using ab initio (HF, DFT and MP2) and the semi-empirical methods (AM1, PM3 and ZINDO). For its molecular structure, HOMO, LUMO, molecular orbital energies and electronic spectra, the theoretical calculations using AM1 (for optimized structure) with ZINDO (for excitation energy) showed results consistent with experimental finding. Further investigation on 1-, 2- and 4-mono-substituted derivatives of pyrene with the effect of the substitution position and the substituents showed: (1) LUMO is decreased when the substituent is an electron acceptor group; (2) HOMO is increased when the substituent is an electron donor group. However, both electron donor and electron acceptor substituents are effective in reducing the energy gap between HOMO and LUMO in the mono-substituted pyrene. In terms of electronic spectra, the transition π→π∗ shows a larger red shift if the substitutions on the pyrene ring are in the 1- and 4-positions. The red shift is even larger if the substituents contain both electron donor and electron acceptor groups. Nevertheless, a slight blue shift would occur, since the substituents are large groups and distort the planar structure of the parent pyrene molecule. This decreases the overlap of the π orbital and hinders the electron transition from π to π∗. According to the above conclusion, semi-empirical AM1 and ZINDO methods in this work predict several electron luminescence materials among pyrene derivatives, and the results agree very well with the experimental findings. Presumably, the procedures of theoretical calculation employed in this study can be successfully applied to investigation on the electroluminescence characteristics of other materials, and further, to design novel materials for organic light emitting diode.|
|Relation: ||Journal of Molecular Structure : Theochem 629(1), pp.11-20|
|Appears in Collections:||[化學學系暨研究所] 期刊論文|
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