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Measurements Combine Electroluminescence with Photoluminescence and Analog Simulation of PET

Author: NiHaiFang
Tutor: LinJiaQi
School: Harbin University of Science and Technology
Course: Materials Physics and Chemistry
Keywords: PET Electroluminescent Photoluminescence Absorption spectrum Simulation
CLC: O631.23
Type: Master's thesis
Year: 2010
Downloads: 51
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Abstract

Polyethylene terephthalate [poly (ethylene terephthalate)-PET] is a milky white or light yellow, surface smooth and shiny, highly crystalline polymers, widely used in electrical insulation materials. The electroluminescent (Electroluminescence-EL) is to convert electricity directly into light phenomenon that is closely related with the space charge. Electroluminescent contribute to the insulating polymer charge injection, transport and storage understand, interpret the electrical aging thresholds and dissipation mechanisms mentioned principles. Photoluminescence (Photoluminescence-PL) is material to absorb a certain amount of light emission caused by the phenomenon, for insulating polymer structure of rare. PET is electrically insulating material, when subjected to strong electric stress time when breakdown occurs due to various reasons, resulting in the insulation end of life. The polymer electrical aging and breakdown involves many factors, and with the structure of matter there is a close relationship between. Electroluminescence and photoluminescence measurements of joint and combined PET computer simulation for understanding the structure, performance and other issues of great significance. In this paper, PET film photoluminescence, photoluminescence and electroluminescence joint measurement, and measure the corresponding UV absorption spectra after excitation; Then, based on first-principles density functional theory (DFT) plane wave pseudopotential method, The electronic structure of PET and optical properties of simulation calculations and compared with experimental results. Measurement results show that: the early accumulation of EL spectra measured 300 ~ 400 nm, 400 ~ 460 nm, 500 ~ 600 nm and 680 nm emission peak exists near. The cumulative attenuation PL intensity variation with time of the exponential decay rate, and the longer the exposure time, the slower decay rate; PL spectra accumulated 300 ~ 400 nm, 500 ~ 600 nm and has a peak around 700nm. PL and EL spectra cumulative joint measurement 300 ~ 400 nm, 400 ~ 460 nm, 500 ~ 600 nm and has a peak at 650 nm, at 450nm near a significant negative EL FET with the previous measurement results. PET film from the absorption edge of the absorption spectrum can be calculated energy band gap is about 3.96eV; while the PL, PL and EL spectra of the calculated joint measurement energy gaps of 3.45eV, 3.57eV. Simulation results show that: PET molecular orbital contributions mainly by O atoms and C atoms 2P 2P orbital tracks, different degree of polymerization by the band structure calculated energy gap than the experimental value of about 2.7eV to 3.96eV partial is small, the deviation within the range of 40%. For the highest occupied molecular orbital, mainly in the charge density on both sides of the benzene ring; the lowest unoccupied orbital, the highest charge density are mainly distributed on the phenyl ring. Absorption spectra obtained by the energy gap and band structure calculations consistent with the results obtained, and to explain the formation of the dielectric function peaks, and other spectral characteristics linked.

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