| The stability and degradation mechanisms of Polymer Light-emitting Diodes(PLEDs) have always been an important topic. Studies on PLEDs are focus on three points: (1)the defects of the PLEDs; (2)degradation in the PLEDs; (3) photovoltaic performance of PLEDs. In order to apply the PLEDs into practical production and our daily life, we shoud start with the next three ways: fisrtly, we must reduce the defects of PLEDs; Secondly, prolong the consenescence and lifetime of PLEDs; In addition, improve the luminescent performance such as reducing the turn-on voltage, increasing the brightness and chroma also can not be ignored. Therefore, researches on defects,degradation and photovoltaic performance of PLEDs have important significance in the development of PLEDs. This thesis studies the defects, degradation mechanisms and the enhancement of the whole performance of the device in the view of devices physics with kinds of spectral methods. We have a deep disscussion into the dagradation mechanism of PLEDs, the structural and performance changes of electrode layers, light-emitting layers and carrier transporting layers, and we also try to find out how to increasing the brightness, efficiency and stability of PLEDs.First of all, the development of OLEDs, the fundamentals and principles about electroluminescence of PLEDs and Raman spectra method are discussed in the first three Chapters.Secondly, Electroluminescence spectra and Raman spectra was used to study voltaic aging of organic light emitting devices with a new kind of conjugated macromolecule polymer emission layer which is called PFO-BT15. Through the test we find, on one hand, the intensity of changeless current flowing across the device have great influence to the speed of its voltage change; On the other hand, after a long time stress, the polymer device's central electroluminescent wavelength has little change; Through Raman test of the devices we suppose that it is the PEDOT anode's breakage which lead to the emission failure of the polymer devices. However the polymer's molecular configuration is unchanged, which indicates that this polymer materials have relatively steady photoelectric performance. This work also brings some helpful information to improve other emission polymer materials' synthesis and their photoelectric performance. In addition, as a popular defect in PLEDs, black spots are studied. Black spots with exponential growth in diameter when external electrical field is applied are the result of losing the effective contact between the polymer layer and metal layer.Thirdly, The effects of thermal annealing on performance and structure of were studied. On the one hand, after annealing of ITO glass with different temperature from 0 to 600℃, we find 400℃annealing could obviously improve the PLEDs'electroluminescence performance; On the other hand, after annealing at the temperature not too far below the glass transition temperature of P-PPV, the luminescent efficiency of the devices increase. when the glass transition temperature reached, the devices' efficiency began to decrease. In condition, through and Reflection and Raman spectra test of the devices we suppose that the polymer's molecular configuration is unchanged, which indicates that this polymer materials have relatively steady thermal physical performance with different annealing temperature.Finally, Raman spectra and infrared imaging system are used to study the internal temperature of PLEDs with different current density. We aim to research the thermal degradation of PLEDs. The accurate internal temperature of PLEDs can be calculated by the proportion of anti-stokes and stokes raman intensity. Therefore, Raman spectra is considered as a good method to detecte the temperature of the thin-film semiconductor device.
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