Effects of organic acids modified ITO anodes on luminescent properties and stability of OLED devices

Abstract

In this paper, p-chlorophenylacetic acid and p-fluorophenylacetic acid were applied to modify the indium tin oxide (ITO) electrodes. The surface work functions of unmodified ITO, p-chlorophenylacetic acid modified ITO (Cl-ITO) and p-fluorophenylacetic acid modified ITO (F-ITO) are 5.0 eV, 5.26 eV and 5.14 eV, respectively, and the water contact angles are 7.3°, 59.1° and 46.5°, respectively. The increase of the work function makes the hole injection ability of the devices improved, which is proved by the hole transport devices. The self-assembly (SAM) layers transfer hydrophilic ITO to hydrophobic ITO, which makes ITO more compatible with the hydrophobic organic layers, making the organic film more stable during the operation. After modification, the organic light emitting diodes (OLEDs), SAM-modified ITO/NPB/Alq3/LiF/Al, with better performance and stability were fabricated. Especially, the OLED with Cl-ITO (Cl-OLED) has a maximum luminance of 22 428 cd/m² (improved by 32.9%) and a half-lifetime of 46 h. Our results suggest that employing organic acids to modify ITO surface can enhance the stability and the luminescent properties of OLED devices.

References

[1] DongK.Y., MingZ., WangJ.J., Xiao-LinW.U., GaoC.Y.. Journal of Functional Materials, 2011, 42: 306

[2] DavidC., TinkhamB.P., PruniciP., PanckowA.. Surface & Coatings Technology, 2017, 314: 113

[3] MermerO., AsciY.. Journal of Optoelectronics & Advanced Materials, 2015, 17: 1339

[4] ZhengH., ZhangF., ZhouN., SunM., LiX., XiaoY., WangS.. Organic Electronics, 2018, 56: 89

[5] S.GP., MoriT.. ESC Journal of Solid State Science and Technology, 2017, 6: R53

[6] JuntaoH.U., YangJ., PengF., MeiW., NiuY.. Semiconductor Optoelectronics, 2017, 38: 16

[7] BulusuA., PaniaguaS.A., MacleodB.A., SigdelA.K., BerryJ.J., OlsonD.C., MarderS.R., GrahamS.. Langmuir the Acs Journal of Surfaces & Colloids, 2013, 29: 3935

[8] BesbesS., LtaiefA., ReybierK., PonsonnetL., JaffrezicN., DavenasJ., OuadaH.B.. Synthetic Metals, 2003, 138: 197

[9] HattonR.A., DayS.R., ChestersM.A., WillisM.R.. Thin Solid Films, 2001, 394: 291

[10] LeihuaX., ZhidanZ., ShuhuaT., LiJ., JinlongL.. Journal of Dispersion Science and Technology, 2012, 33: 1093

[11] JeongD., LimC., KimM., JeongK., KimJ.-H., KimJ., ParkJ.-G., MinK.-S., LeeJ.. Electronic Materials Letters, 2017, 13: 16

[12] BardeckerJ.A., MaH., KimT., HuangF., LiuM.S., ChengY.J., TingG., JenK.Y.. Advanced Functional Materials, 2008, 18: 3964

[13] CanM., HavareA.K., AydinH., YagmurcukardesN., DemicS., IcliS., OkurS.. Applied Surface Science, 2014, 314: 1082

[14] MuS.G., SongJ.M., KimC., LeeJ., KimJ., MiJ.L.. Electronic Materials Letters, 2015, 11: 252

[15] ZhaoY., DuanL., ZhangD., DongG., QiaoJ., WangL., QiuY.. Acs Applied Materials & Interfaces, 2014, 6: 4570

[16] LeeJ., JungB.J., LeeJ.I., ChuH.Y., DoL.M., ShimH.K.. Journal of Materials Chemistry, 2002, 12: 3494

[17] ChongL.W., LeeY.L., WenT.C.. Thin Solid Films, 2007, 515: 2833

[18] D’AndradeB.W., EslerJ., BrownJ.J.. Synthetic Metals, 2006, 156: 405

[19] ZuppiroliL., Si-AhmedL., KamarasK., NüeschF., BussacM.N., AdesD., SioveA., MoonsE., GrätzelM.. The European Physical Journal B - Condensed Matter and Complex Systems, 1999, 11: 505

Just Accepted

This article has successfully passed peer review and final editorial review, and will soon enter typesetting, proofreading and other publishing processes. The currently displayed version is the accepted final manuscript. The officially published version will be updated with format, DOI and citation information upon launch. We recommend that you pay attention to subsequent journal notifications and preferentially cite the officially published version. Thank you for your support and cooperation.