Dissertation > Excellent graduate degree dissertation topics show

Density Functional Theory Study on Organic Complex Phosphorescent Materials with Iridium Core

Author: LinYang
Tutor: YangLiXin
School: Xiangtan University
Course: Inorganic Chemistry
Keywords: Tris (2 - phenylpyridine) iridium benzo derivatives Tris ( 1 - phenyl - pyrazolyl) iridium fluorinated derivative The structure of the ground state Absorption and emission properties TDDFT
CLC: O621.13
Type: Master's thesis
Year: 2009
Downloads: 46
Quote: 0
Read: Download Dissertation

Abstract

With the rapid development of computational methods and computer technology, computational chemistry plays an increasingly important role in the chemical study. Density functional methods are widely used in the study of metal organic and inorganic molecular nature of the ground state, while containing the development of density functional theory for the calculation of the excited states of an effective way. In recent years, electroluminescence phosphorescent organic light emitting device with its can use the singlet and triplet excitons and reached 100% of the internal quantum efficiency and popular attention. Iridium core electroluminescent phosphorescent material is by virtue of a suitable phosphorescent life, less affected self-quenching and efficient luminescent efficiency advantage of experimental and theoretical research hot spots. For electroluminescent phosphorescent material preparation, ligand design molecules smaller energy difference caused difficulties and low luminous efficiency of blue phosphorescent material two major problems, the paper using the Gaussian program, take the density functional theory method of tris (2 - phenylpyridine) iridium benzo derivatives, and tri (1 - phenyl-pyrazol) iridium fluorinated derivative two types of organic complexes phosphorescent material for analysis, organic nature of the phosphorescent material for further study of iridium as the core electrical Narrow regulation the emission chromaticity and improve the efficiency of light-emitting provides a strong theoretical foundation. Using the Functional Theory B3LYP/LANL2DZ method Opposite - tris (2 - phenylpyridine) iridium (1), and introducing a benzo ring formation at the 2 - phenylpyridine ligand derivative (2-8) optimize the structure of the ground state, and by time-dependent density functional theory study luminescence properties of these complexes. The eight kinds of molecules are presented C3 symmetry, the dihedral angle between the plane of the benzene ring and pyridine ring 2 (6.29 °) → 3 (1.90 °) → 4 (12.76 °) Trends and 8 (6.98 °) → 7 (1.17 °) → 6 (12.83 °) of the similar trend. Increase 2 - phenylpyridine ligand π-conjugated range has little effect on the HOMO energy of the complexes, but can significantly reduce the LUMO energy, especially benzo structure is formed on the pyridine ring of the ligand. The energy gap between the HOMO and LUMO according gt; 2 gt; 4 gt; 5 gt; 3 gt; 8 gt; 6 gt; reduced the order of 7, which makes the 2-8 absorption spectrum obviously redshift. Triplet excitation wavelength of T1 1 lt; 5 lt; 2 lt; 4 lt; 3 lt; 8 lt; 7 lt; 6 order change emission spectra redshift can be fine-tuned from 36 nm to 108 nm, 6 and 7 from the three-line state to the singlet of the phosphorescent emission moved to 602.6 nm and 572.7 nm respectively, show that the luminescent color from green to red electrically calculated within an error of 20 nm, it is feasible through the series of the benzo derivatives prediction and control. Using density functional theory B3LYP method the LANL2DZ yl group, opposite the formula - Three (1 - phenyl-pyrazolyl) iridium (1) and on the pyrazole ring ligand introduction of a trifluoromethyl group or a fluorine atom form a fluorinated derivative (2-7) ground state structure optimization, and through the time-dependent density functional theory to study the nature of the absorption and emission spectra of these complexes. Seven kinds of molecules are C3 Symmetry stable structure, the fluorination of the dihedral angle between the benzene ring and a pyrazole ring is small, but it makes the HOMO and LUMO level reduced, especially on the pyrazole ring introduced trifluoromethyl. Energy gap between the HOMO and the LUMO follow 5 gt; 7 gt; gt; 6 gt; 3 gt; 2 gt; 4 variation, which makes the 2, 3, 4 and 6 of the absorption and emission spectra red shift 5 and 7 of the absorption and emission spectra blue shift. Introduced at the 3 and 5 of the pyrazole ligand tris (1 - phenyl-pyrazolyl) iridium the CF3, there is possible to obtain the blue phosphorescent material having a high luminous efficiency.

Related Dissertations

CLC: > Mathematical sciences and chemical > Chemistry > Organic Chemistry > Organic Chemistry general issues > Theory of organic chemistry,physical organic chemistry > Organic Chemistry Structure Theory
© 2012 www.DissertationTopic.Net Mobile