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A novel method for the subdivision of ITO glass substrates
Synthetic Metals 111–112 Ž2000. 385–386 www.elsevier.comrlocatersynmet
A novel method for the subdivision of ITO glass substrates Dirk Hohnholz, Karl-Heinz Schweikart, Michael Hanack ) Institut fur Auf der Morgenstelle 18, 72076 Tubingen, Germany ¨ Organische Chemie, Lehrstuhl II, UniÕersitat ¨ Tubingen, ¨ ¨
Abstract Subdivision of indium tin oxide ŽITO. covered glass substrates can be easily carried out by a localized destruction of the ITO under a tungsten needle, applying a voltage between the ITO and the needle tip. The necessary equipment can be set up with commercially available components. The scorched lines almost completely insulate the different segments from each other. Using this method almost, every pattern can be printed into the ITO layer by a computer aided design ŽCAD. software in combination with a flatbed plotter, by application of a template or by free hand treatment. q 2000 Elsevier Science S.A. All rights reserved. Keywords: Structured indium tin oxide ŽITO.; Organic light-emitting diodes ŽOLEDs.
1. Introduction The most common conductive substrate for organic light-emitting diodes ŽOLEDs. is indium tin oxide ŽITO. as a transparent anode, deposited on glass carriers. To obtain imaging structures, e.g. seven-segment displays or dot matrix displays, either the metal cathode or the ITO anode must be subdivided. Also, for research purposes, it is advantageous to divide electrodes in order to gain several devices within one carrier and, thus, to increase reproducibility and the amount of research data. We present a new and simple technique based on the localized destruction of the ITO layer of commercially available substrates. w1–4x Fig. 1. Photograph of a seven-segment OLED based on a subdivided ITO.
2. Results and discussion Fig. 1 shows a seven-segment OLED based on a subdivided ITO substrate Žtwo segments are not biased.. The localized removal of the ITO layer Žbarely visible white lines. is achieved by application of a voltage, e.g. 15 V, between a tungsten needle and the conductive ITO substrate. When in contact, the resulting high current density in the needle tip causes a local elevated temperature, which is expected to be much higher than the decomposition
) Corresponding author. Tel.: q49-7071-2978743; fax: q49-7071295244; http:rrwww.uni-tuebingen.derhanackrindex.html. E-mail address: [email protected] ŽM. Hanack..
point of ITO ŽIn 2 O 3 sublimes above 8508C, the decomposition point of SnO 2 in air is approximately 15008C w5x.. The ITO subdivision equipment, which can be set up with commercially available components, is depicted in Fig. 2. The ITO plate Ž1. is fixed in a flatbed plotter Ž2.. The complete perimeter of an aluminium frame Ž3. establishes contact between the ITO layer and the positive pole of a power supply Ž4. along the full length of its border. A tungsten needle Ž5. is fixed in a metal plotter pen Ž6. and connected to the negative pole of the supply Ž4.. With this assembly structural plots can be generated by means of computer aided design ŽCAD. software on a computer Ž7.. Almost any type of pattern, script or image can be drawn and then transferred onto the ITO substrate Ž1.. Depending
0379-6779r00r$ - see front matter q 2000 Elsevier Science S.A. All rights reserved. PII: S 0 3 7 9 - 6 7 7 9 Ž 9 9 . 0 0 3 3 4 - 3
386
D. Hohnholz et al.r Synthetic Metals 111–112 (2000) 385–386
treated with hydrochloric acid, water, acetone and chloroform to remove residues of decomposition products and is ready for a variety of applications including OLEDs. In conclusion, the presented method of electrical scorching is suitable for the subdivision of ITO covered glass substrates. This procedure is simple to perform and allows the generation of complex structures on commercial ITO substrates.
References Fig. 2. Schematic diagram of the apparatus used to subdivide ITO.
upon the desired exactness, structures can also be implemented using a template or by free hand. By this process the ITO layer is separated into independent segments. The width of the scorched lines is determined via AFM measurement to be in the range of 100 mm, depending on the applied voltage. w6x The subdivided ITO substrate is then
w1x J. Hu, R.G. Beck, R.M. Westervelt, G.M. Whitesides, Adv. Mater 10 Ž1998. 574. w2x Kohlrausch, in: Praktische Physik 2 Teubner, Stuttgart, 1985. w3x M. Strukelj, T.M. Miller, F. Papadimitrakopoulos, S. Son, J. Am. Chem. Soc 117 Ž1995. 11976. w4x S. Fiedler, S. Shirley, T. Schnelle, Sens. Mater 9 Ž1997. 141. w5x A. Dietzel, W. Poch, Radex Rundsch. 1 Ž1960. 52. w6x D. Hohnholz, K.-H. Schweikart, M. Hanack, Adv. Mater. 11 Ž1999. 646.
A novel method for the subdivision of ITO glass substrates Dirk Hohnholz, Karl-Heinz Schweikart, Michael Hanack ) Institut fur Auf der Morgenstelle 18, 72076 Tubingen, Germany ¨ Organische Chemie, Lehrstuhl II, UniÕersitat ¨ Tubingen, ¨ ¨
Abstract Subdivision of indium tin oxide ŽITO. covered glass substrates can be easily carried out by a localized destruction of the ITO under a tungsten needle, applying a voltage between the ITO and the needle tip. The necessary equipment can be set up with commercially available components. The scorched lines almost completely insulate the different segments from each other. Using this method almost, every pattern can be printed into the ITO layer by a computer aided design ŽCAD. software in combination with a flatbed plotter, by application of a template or by free hand treatment. q 2000 Elsevier Science S.A. All rights reserved. Keywords: Structured indium tin oxide ŽITO.; Organic light-emitting diodes ŽOLEDs.
1. Introduction The most common conductive substrate for organic light-emitting diodes ŽOLEDs. is indium tin oxide ŽITO. as a transparent anode, deposited on glass carriers. To obtain imaging structures, e.g. seven-segment displays or dot matrix displays, either the metal cathode or the ITO anode must be subdivided. Also, for research purposes, it is advantageous to divide electrodes in order to gain several devices within one carrier and, thus, to increase reproducibility and the amount of research data. We present a new and simple technique based on the localized destruction of the ITO layer of commercially available substrates. w1–4x Fig. 1. Photograph of a seven-segment OLED based on a subdivided ITO.
2. Results and discussion Fig. 1 shows a seven-segment OLED based on a subdivided ITO substrate Žtwo segments are not biased.. The localized removal of the ITO layer Žbarely visible white lines. is achieved by application of a voltage, e.g. 15 V, between a tungsten needle and the conductive ITO substrate. When in contact, the resulting high current density in the needle tip causes a local elevated temperature, which is expected to be much higher than the decomposition
) Corresponding author. Tel.: q49-7071-2978743; fax: q49-7071295244; http:rrwww.uni-tuebingen.derhanackrindex.html. E-mail address: [email protected] ŽM. Hanack..
point of ITO ŽIn 2 O 3 sublimes above 8508C, the decomposition point of SnO 2 in air is approximately 15008C w5x.. The ITO subdivision equipment, which can be set up with commercially available components, is depicted in Fig. 2. The ITO plate Ž1. is fixed in a flatbed plotter Ž2.. The complete perimeter of an aluminium frame Ž3. establishes contact between the ITO layer and the positive pole of a power supply Ž4. along the full length of its border. A tungsten needle Ž5. is fixed in a metal plotter pen Ž6. and connected to the negative pole of the supply Ž4.. With this assembly structural plots can be generated by means of computer aided design ŽCAD. software on a computer Ž7.. Almost any type of pattern, script or image can be drawn and then transferred onto the ITO substrate Ž1.. Depending
0379-6779r00r$ - see front matter q 2000 Elsevier Science S.A. All rights reserved. PII: S 0 3 7 9 - 6 7 7 9 Ž 9 9 . 0 0 3 3 4 - 3
386
D. Hohnholz et al.r Synthetic Metals 111–112 (2000) 385–386
treated with hydrochloric acid, water, acetone and chloroform to remove residues of decomposition products and is ready for a variety of applications including OLEDs. In conclusion, the presented method of electrical scorching is suitable for the subdivision of ITO covered glass substrates. This procedure is simple to perform and allows the generation of complex structures on commercial ITO substrates.
References Fig. 2. Schematic diagram of the apparatus used to subdivide ITO.
upon the desired exactness, structures can also be implemented using a template or by free hand. By this process the ITO layer is separated into independent segments. The width of the scorched lines is determined via AFM measurement to be in the range of 100 mm, depending on the applied voltage. w6x The subdivided ITO substrate is then
w1x J. Hu, R.G. Beck, R.M. Westervelt, G.M. Whitesides, Adv. Mater 10 Ž1998. 574. w2x Kohlrausch, in: Praktische Physik 2 Teubner, Stuttgart, 1985. w3x M. Strukelj, T.M. Miller, F. Papadimitrakopoulos, S. Son, J. Am. Chem. Soc 117 Ž1995. 11976. w4x S. Fiedler, S. Shirley, T. Schnelle, Sens. Mater 9 Ž1997. 141. w5x A. Dietzel, W. Poch, Radex Rundsch. 1 Ž1960. 52. w6x D. Hohnholz, K.-H. Schweikart, M. Hanack, Adv. Mater. 11 Ž1999. 646.