Effect of Al:Ag alloy cathode on the performance of transparent organic light-emitting devices

Abstract

Transparent organic light-emitting devices (TOLEDs) based on a stacked alloy cathode of LiF/Al:Ag are investigated. The devices have a structure of indium-tin-oxide (ITO)/4,4′,4″-Tris[2-naphthyl(phenyl)amino]triphenylamine (2T-NATA) (25 nm)/N,N′-Di-[(1-naphthyl)-N,N′-diphenyl]-1,1’-biphenyl-4,4′-diamine (NPB) (40 nm)/tris-(8-hydroxyquinoline) aluminum (Alq₃) (50 nm)/LiF (1 nm)/Al:Ag (1:3) (x), where the thicknesses of cathode metal layers (Al:Ag) are adjusted, respectively, from 70 nm to 100 nm. In the experiment, it is found that the LiF (1 nm)/Al:Ag (1:3) (75 nm) has good electron injection efficiency. Compared with an Al-only cathode, the turn-on voltage is lowered. At the voltage of 10 V, the luminances for bottom emission from ITO anode side and top emission from metal cathode side are 2 459 cd/m² and 1 729 cd/m², respectively. Thanks to electron injection enhancement by using Al:Ag cathode, we can obtain a better energy level matching between the cathode and the organic layer, thus the devices have lower turn-on voltage and higher luminance. The total transmittance of the devices can achieve about 40% at the wavelength of 550 nm.

References

[1] ChenJ X, ChenJ D, WuZ Z. White OLED for Lighting, 2011, Shanghai, Shanghai Jiao Tong University Press, 142

[2] LinC-D, ChittawanijA, HongL-A, WangC-C, LaiS-H, TsaiY-S, JuangF-S. The Study of Transparent Organic Light-Emitting Diodes with Two Side Emitting, 2015, Taipei, Taiwan, The 14th IFToMM World Congress, 25

[3] FujimotoH, MiyayamaT, SanadaN, AdachiC. Organic Electronics, 2013, 14: 2994

[4] ImJ H, KangK-T, LeeS H, HwangJ Y, KangH, ChoK H. Organic Electronic, 2016, 33: 116

[5] ZhangZ, YanP, YueS, XieG, ChenY, WuQ, QuD, ZhaoY, LiuS. Organic Electronics, 2013, 14: 1452

[6] NohJ H, HwangB H, KimC S, JoS J, KimJ T, HwangH S, BaikaH K. Applied Physics Letters, 2008, 92: 023306

[7] KumarG, LiY-D, BiringS, LinY-N, LiuS-W, ChangC-H. Organic Electronics, 2017, 42: 52

[8] TaoY, LiJ, LiK, WangH, ChenP, DuanY-H, ChenZ, LiuY-F, WangH-R, DuanY. Organic Electronics, 2017, 41: 179

[9] PodeR B, LeeC J, MoonD G, HanJ I. Appl. Phys. Lett., 2004, 84: 4614

[10] MAH, LID-h, CHENW-b, YEJ-x. Journal of Optoelectronics·Laser, 2016, 27: 681

[11] DUS, ZHANGF-h. Journal of Optoelectronics·Laser, 2017, 28: 19

[12] ParkM J, SonY H, KimG H, LampandeR, BaeH W, PodeR, LeeY K, SongW J, KwonJ H. Organic Electronics, 2015, 26: 458

[13] PschenitzkaF. Method of Tuning Work Function of Metal Nanostructure-Based Transparent Conductor, 2012,

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.