Measurements Combine Electroluminescence With Photoluminescence And Analog Simulation Of Pet

[Poly (ethylene terephthalate)-PET] milky white or yellow, height crystalline polymer and Surface smooth sheen is widely used in electric insulation. Electroluminescence (EL) is a phenomenon that converts the electricity to light directly, with which is closely connected the space charge. Electroluminescence helps to understanding the charge-injection, charge-transmission and charge-storage in the insulating polymer, explaining the threshold value of electrical ageing and the dissipative mechanism as well as providing advice to monitor the aging rate at the same time. Photoluminescence (PL) is a kind of luminescence caused by the substance absorbing a certain amount of luminous energy. It has been used in mineral luminescence for a long time. PET is electric insulation. It maybe broken down for many reasons and leads to end of its life when it is exposed to stress for a long time. The electrical ageing and breaking down of polymers involve in many factors, which have close relation with the structure of the substances. The Measurements Combine Electroluminescence with Photoluminescence and Analog Simulation has a great significant for understanding the structure and performent of PET.In this paper, the photoluminescence (PL) and the measure combined photoluminescence (PL) with electroluminescence (EL) of Poly (ethylene Terephthalate) -PET films were detected, and the corresponding excited of UV-Vis absorbing spectra was measured. Compared with the experimental results, the electron structure and optical properties was calculated base on first principles density function theory (DFT).The results show that there were peaks in 300~400nm,400~460nm,500~600nm and nearby 680nm in preceding EL measurement. The PL intensity decay meets an exponential to decay with time goes on. The PL accumulative spectra have peaks in about 300 ~400nm,500~600nm and 700nm. The combined measure of EL and PL spectra have peaks in about 300~400nm,400~460nm,500~600nm and nearby 650nm, yet there was a apparent negative fields nearby 450nm. In agreement with the preceding EL measurement.The optical energy gap (E_g) of PET films is about 3.96eV from calculating the absorbing edge of absorbing spectra. For the PL and the combined PL with EL spectra, the band gap is 3.45 and 3.57, respectively. Analog result indicates that Molecules orbit contribution of PET are derived from carbon 2p orbital and oxygen 2p orbital, respectively. However the band gap from the energy band structure is 2.7eV much smaller than the experimental value 3.96eV, yet the deviation within the range of 40%. For the Highest Occupied Molecular Orbital,the Charge density is mainly distributed in the both sides of the benzene ring. However, for the Lowest Unoccupied Molecular Orbital, the Charge density is mainly distributed on the benzene ring. The band gap calculated from the absorption edge of absorption spectra is in agreement with the result of the energy band structure. Furthermore, the relationship between the formation of dielectric function peaks and other spectral characteristics was interpreted.Analog result indicates that Molecules orbit contribution of PET are derived from carbon 2p orbital and oxygen 2p orbital, respectively. However the band gap from the energy band structure about 2.7eV is much smaller than the experimental value. For the Highest Occupied Molecular Orbital,the Charge density is mainly distributed in the both sides of the benzene ring. However, for the Lowest Unoccupied Molecular Orbital, the Charge density is mainly distributed on the benzene ring. The band gap calculated from the absorption edge of absorption spectra is in agreement with the result of the energy band structure. Furthermore, the relationship between the formation of dielectric function peaks and other spectral characteristics was interpreted.