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- Polymer light emitting devices with Langmuir Blodgett (LB) films of a polyfluorene derivative
- Universidade Estadual Paulista (UNESP)
- Universidade Federal do Paraná (UFPR)
- Universidade de São Paulo (USP)
- Polyfluorenes are promising materials for the emitting layer of polymer light emitting devices (PLEDs) with blue emission. In this work, we report on PLEDs fabricated with Langmuir-Blodgett (LB) films of a polyfluorene derivative, namely poly(9,9-di-hexylfluorenediyl vinylene-alt-1,4-phenylenevinylene) (PDHF-PV). Y-type LB films were transferred onto ITO substrates at a surface pressure of 35 mN m-1 and with dipping speed of 3 mm min -1. A thin aluminum layer was evaporated on top of the LB film, thus yielding a sandwich structure (ITO/PDHF-PV(LB)/Al). Current-voltage (I vs V) measurements indicate that the device displays a classical behavior of a rectifying diode. The threshold value is approximately 5 V, and the onset for visible light emission occurs at ca. 10 V. From the a.c. electrical responses we infer that the active layer has a typical behavior of PLEDs where the real component of ac conductivity obeys a power-law with the frequency. Cole-Cole plots (Im(Z) vs. Re(Z)) for the device exhibit a series of semicircles, the diameter of which decreases with increasing forward bias. This PLED structure is modeled by a parallel resistance and capacitance combination, representing the dominant mechanisms of charge transport and polarization in the organic layer, in series with a resistance representing the ITO contact. Overall, the results presented here demonstrate the feasibility of LEDs made with LB films of PDHF-PV.
- Proceedings - International Symposium on Electrets, v. 2005, p. 438-440.
- Langmuir Blodgett films
- Light emitting diodes
- Polymer films
- Sandwich structures
- Blue emissions
- Polyfluorene derivative
- Polymer light emitting devices (PLED)
- Surface pressure
- Inorganic polymers
- Acesso restrito
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