| An organic light-emitting field-effect transistor (OLET), which combines the current modulating function of an OFET with the electroluminescence of an organic light-emitting diode (OLED) in a single device, has been invented recently. OLETs are promising for the development of simplified pixels for flat panel displays, optical communication devices, and electrically driven organic lasers. Unipolar or ambipolar OLETs based on a number of molecular and polymeric semiconductors were reported, which emitted light covering the visible and near infrared region of the spectrum.In this thesis, the pentacene-based organic field-effect transistors (OFETs) with poly(methyl methacrylate)(PMMA) as gate dielectrics were fabricated, and the effects of gate dielectric thickness and semiconductor thickness on the device performance were investigated. The optimal PMMA thickness is in the range of350～400nm to sustain a considerable current density and stable performance. The device performance depends on the thicknesses of the active layer non-monotonically, which can be explained by the morphology of the pentacene film and the position of the conducting channel in the active layer. The device with a pentacene thickness of50nm shows the best performance, which has a maximum hole mobility of1.12cm2/V·s. In addition, the introduction of a thin layer of tris-(8-hydroxyquinolinato) aluminum (Alq3) to the OFETs as a light-emitting material greatly decreases the device performance.In order to enhance the device performance of the OLETs based on Alq3and pentacene, asymmetrical electrodes that can increase electron injection were investigated.It is found that the most effective asymmetrical electrodes are Au and LiF-Al. The OLET with such electrodes has a maximum hole mobility of0.38cm2/V·s and a maximum current of19.6μA. And last, A new structure OLET with the Au/LiF-Al electrodes was fabricated, and light emission from the Alq3layer has been observed by a naked eye in a bright room. |
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