Indium–tin oxide treatments for single- and double-layer polymeric light-emitting diodes: The relation between the anode physical, chemical, and morphological properties and the device performance

Journal of Applied Physics - Tập 84 Số 12 - Trang 6859-6870 - 1998
Ji‐Seon Kim1, Magnus Granström1, Richard H. Friend1, Nils Johansson2, W. R. Salaneck2, Rusli Daik3, W. James Feast3, Franco Cacialli1
1Cavendish Laboratory, Madingley Road, Cambridge CB3 0HE, United Kingdom
2Department of Physics, IFM, Linköping University, S-518 83 Linköping, Sweden
3IRC Polymer Science and Technology, Durham University, South Road, Durham DH1 3LE, United Kingdom

Tóm tắt

We report combined studies of the influence of chemical and physical treatments on the properties of indium–tin oxide (ITO) thin films. The ITO films were also used as transparent anodes of polymeric light-emitting diodes (LEDs) incorporating poly(p-phenylene vinylene) (PPV) as the emitter material, with, or without, doped poly(3,4-ethylene dioxythiophene) (PEDOT) as a hole-injection/transport layer. Structures based on a soluble green derivative of PPV, poly(4,4′-diphenylene diphenylvinylene) were also tested. We studied chemical (aquaregia, degreasing, RCA protocol) and physical (oxygen and argon plasmas, Teflon, and paper rubbing) treatments and, in contrast to recently published work, we find that for Balzer Baltracon ITO, oxygen plasma and not aquaregia yields the highest efficiencies and luminances and the lowest drive voltages. For oxygen-plasma-treated anodes, the device efficiency clearly correlates with the value of the ITO surface work function, which in turn depends on the time of treatment. Interestingly, we find that work-function variations induced by our oxygen-plasma treatment are unchanged after long-term storage in air and in the dark. Unexpectedly, we also find that devices incorporating a PEDOT layer benefit from an appropriate treatment of the ITO surface, for both efficiency and lifetime. The results shed light on the physics of conjugated, organic semiconductors and related devices, and in particular on the presence and the role of an anodic energy barrier on the LEDs mechanism of operation. We also discuss the implications of our integrated experimental study in relation to the modification of the ITO sheet resistance, surface and bulk composition, and surface morphology.

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Tài liệu tham khảo

1990, Nature (London), 347, 539, 10.1038/347539a0

1987, Appl. Phys. Lett., 51, 913, 10.1063/1.98799

1994, Synth. Met., 67, 157, 10.1016/0379-6779(94)90031-0

1995, Jpn. J. Appl. Phys., Part 2, 34, L824, 10.1143/JJAP.34.L824

1995, Synth. Met., 73, 195, 10.1016/0379-6779(95)80015-8

1996, Appl. Phys. Lett., 69, 394, 10.1063/1.118072

1995, Appl. Phys. Lett., 66, 2679, 10.1063/1.113123

1996, Mol. Cryst. Liq. Cryst. Sci. Technol., Sect. A, 283, 57, 10.1080/10587259608037864

1996, J. Appl. Phys., 79, 2745, 10.1063/1.361096

1996, Synth. Met., 80, 7, 10.1016/0379-6779(96)03660-0

1996, Trends Polym. Sci., 4, 151

1996, Appl. Phys. Lett., 69, 2894, 10.1063/1.117354

1997, Macromol. Chem. Phys., 198, 1437, 10.1002/macp.1997.021980512

1997, Appl. Phys. Lett., 71, 34, 10.1063/1.119483

1997, Proc. SPIE, 3148, 264, 10.1117/12.279343

1996, Appl. Phys. Lett., 69, 2160, 10.1063/1.117151

1997, Appl. Phys. Lett., 70, 1665, 10.1063/1.118664

1996, Synth. Met., 76, 125, 10.1016/0379-6779(95)03434-L

1986, J. Appl. Phys., 60, R123, 10.1063/1.337534

1992, J. Mater. Sci. Lett., 11, 263, 10.1007/BF00729407

1997, Appl. Phys. Lett., 71, 1145, 10.1063/1.119848

1996, Synth. Met., 80, 111, 10.1016/S0379-6779(96)03690-9

1997, Appl. Phys. Lett., 70, 1348, 10.1063/1.118575

1997, Jpn. J. Appl. Phys., Part 1, 36, 350, 10.1143/JJAP.36.350

1997, Appl. Phys. Lett., 70, 2741, 10.1063/1.119008

1997, Synth. Met., 91, 99, 10.1016/S0379-6779(97)03986-6

1993, Acta Polym., 44, 201, 10.1002/actp.1993.010440405

1996, Acta Polym., 47, 436, 10.1002/actp.1996.010471003

1985, Synth. Met., 10, 181, 10.1016/0379-6779(85)90189-4

1991, Synth. Met., 41, 831, 10.1016/0379-6779(91)91506-6

1992, Adv. Mater., 4, 116, 10.1002/adma.19920040213

1997, Synth. Met., 89, 161, 10.1016/S0379-6779(97)81212-X

1975, Top. Appl. Phys., 4, 25

1997, Adv. Mater., 9, 230, 10.1002/adma.19970090308

1998, Adv. Mater., 10, 77

1993, J. Appl. Phys., 73, 4344, 10.1063/1.352818

1995, Chem. Phys. Lett., 241, 89, 10.1016/0009-2614(95)00584-Q

1993, Synth. Met., 55–57, 434

1998, Opt. Mater., 9, 125, 10.1016/S0925-3467(97)00082-7

1997, Appl. Phys. Lett., 70, 2067, 10.1063/1.118953

1997, J. Appl. Phys., 82, 1454, 10.1063/1.365923

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Thông tin xuất bản

Journal of Applied Physics

Tập 84 Số 12

6859-6870

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