| Summary: | 碩士 === 國立成功大學 === 電機工程研究所 === 83 === In this work we will discuss the operation and internal states
of AC thin film electroluminescent ( ACTFEL ) devices. First,
functions of internal states have been derived using
electromagnetic theory, such as phosphor field and interface
charge. Then, we measure in practice, get some curves by a
digital oscilloscope, manipulate them by PC in advance, and
compare them with those of ideal cases. The leakage is found to
play an important role in the operation of EL devices. Not
only serious effects on charge, current, and capacitance
characteristics, it also suggests a clue of the operation of EL
devices. In this paper, the equivalent device capacitance is
used to explain and discuss some strange situations in
characteristic curves we got and why they exist, in a
systematic manner. Here we use also a simple method to fit
interface charge versus time curves, and from it a rough
distribution of the interface state, under steady driving is
calculated out. The same, the leakage affects the result of
calculation again. In addition, by the practical measurement of
the efficiency and brightness, the effect of the leakage on the
excitation efficiency and the existance of the optimum
thickness of the insulating layers are confirmed also. All
these point out the importance of the leakage on
characteristics of EL devices.
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