Poly(p-phenylene vinylene) light-emitting devices prepared via the precursor route onto indium tin oxide and fluorine-doped tin dioxide substrates
- 113 Downloads
For the preparation of organic light-emitting devices (LEDs) an optically transparent and electrically conducting thin film is needed as anode. Usually, a glass substrate coated with indium tin oxide (ITO) is used. We show that ITO is unsuitable in the case of poly(p-phenylene vinylene) (PPV) prepared by the precursor route. We have found that a reaction in which hydrogen chloride is eliminated during the thermal conversion to PPV and the ITO takes place. Scanning electron microscopy investigations of the ITO-PPV interface demonstrates that indium chloride compounds, e.g., InCl3 crystals with dimensions up to 40 μm, are produced. Photoluminescence measurements reveal that the fluorescence efficiency is quenched by a factor of 2–23 in the case of ITO compared with PPV converted onto usual glass. In a second step we have investigated LEDs prepared from PPV in the ITO/PPV/Al configuration in order to obtain information about the process responsible for the degradation of these devices. We shall show that the formation of the above-mentioned indium chloride compounds is one possible degradation mechanism and is responsible for the relative short lifetimes of these LEDs. To overcome this problem we propose to use fluorine-doped tin dioxide (FTO) instead of ITO. Finally, we show the results obtained for LEDs in the FTO/PPV/Al configuration and compare them with ITO/PPV/Al devices.
KeywordsIndium Oxide Thermal Conversion Phenylene Vinylene Onset Voltage Tetrahydrothiophene
Unable to display preview. Download preview PDF.
- 3.I. MURASE, T. OHNISHI, T. NOGUCHI and M. HIROOKA, Polym. Commun. 25 (1984) 327.Google Scholar
- 26.W. RIEß, S. KARG, M. MEIER, M. CÖLLE and J. GMEINER, in Technical Digest of the International Symposium on Inorganic and Organic Electroluminescence, 1994 (Hamamatsu, Tottori University, Tottori, 1994) p. 84.Google Scholar
- 28.J. R. BELLINGHAM, W.A. PHILLIPS and C.J. ADKINS, J. Phys.: Condens. Matter 2 (1990) 6207.Google Scholar
- 30.A. F. HOLLEMAN and E. WIBERG, “Lehrbuch der Anorganischen Chemie” (Walter de Gruyter, Berlin, 1985) p. 891.Google Scholar
- 32.L. GMELIN, “Gmelins Handbuch der anorganischen Chemie” (Chemie Weinheim, Weinstrasse, 1971) System-Nr. 46, Teil C1, 98.Google Scholar