Efficient double-emitting layer inverted organic light-emitting devices with different spacer layers

Abstract

Double-emitting layer inverted organic light-emitting devices (IOLEDs) with different spacer layers were investigated, where 2,20,7,70-tetrakis(carbazol-9-yl)-9,9-spirobifluorene (CBP), 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP), 4,7-diphenyl-1,10-phenanthroline (Bphen) and 4,40,400-tris(N-carbazolyl)-triphenylamine (TCTA) were used as spacer layers, respectively, and GIr1 and R-4b were used as green and red guest phosphorescent materials, respectively. The results show that the device with BCP spacer layer has the best performance. The maximum current efficiency of the BCP spacer layer device reaches up to 24.15 cd·A^-1 when the current density is 3.99 mA·cm^-2, which is 1.23 times bigger than that of the CBP spacer layer device. The performance is better than that of corresponding conventional device observably. The color coordinate of the device with BCP spacer layer only changes from (0.625 1, 0.368 0) to (0.599 5, 0.392 8) when the driving voltage increases from 6 V to 10 V, so it shows good stability in color coordinate, which is due to the adoption of the co-doping evaporation method for cladding luminous layer and the effective restriction of spacer layer to carriers in emitting layer.

References

[1] TakadaM, FurutaS, KobayashiT, NagaseT, ShinagawaT, IzakiM, NaitoH. Journal of Applied Physics, 2016, 120: 185501

[2] OuP, YangG, JiangQ, YuJ-s, WuQ-p, ShangF-h, YinW, WangJ, ZhongJ, LuoK-j. Optoelectronics Letters, 2009, 5: 329

[3] ChoiH W, KimS Y, KimW K, LeeJ L. Applied Physics Letters, 2005, 87: 082102

[4] LinH, YuJ-s, ZhangW. Optoelectronics Letters, 2012, 8: 197

[5] HuangW, MiB-x, GaoZ-q. Organic Electronics, 2011, Beijing, Science Press, 292

[6] ChenJ-x, ChenJ-d, WuZ-z. White OLED for Lighting, 2011, Shanghai, Shanghai Jiao Tong University Press, 142

[7] LiS-J, LiY-F. Journal of Optoelectronics ·Laser, 2013, 24: 11

[8] SchwartzG, ReinekeS, WalzerK, LeoK. Applied Physics Letters, 2008, 92: 053311

[9] SeoJ H, ParkJ S, LeeS J, SeoB M, LeeK H, ParkJ K, YoonS S, KimY K. Current Applied Physics, 2011, 11: 564

[10] WangQ, DingJ-q, MaD-g, ChengY-x, WangL-x, JingX-b, WangF-s. Advanced Functional Materials, 2009, 19: 84

[11] LiH-k, ZhangF-h, ChengJ, DingL. Chinese Journal of Luminescence, 2016, 37: 38

[12] HwangM C, ThangarajuK, SoK H, ShinS C, KwonS K. Synthetic Metals, 2012, 162: 391

[13] AcharyaR, CaoX A. Applied Physics Letters, 2012, 101: 3844

[14] YookK S, LeeJ Y. Journal of Industrial and Engineering Chemistry, 2010, 16: 181

[15] YangH-s, WuL-s. Optoelectronics Letters, 2017, 13: 29

[16] ChenZ, DengZ-b. Optoelectronics Letters, 2015, 11: 187

[17] ZhangW, ZhangF-h, HuangJ. Spectroscopy and Spectral Analysis, 2014, 34: 322

[18] WangL, WuY, ShanG-g, GengY, ZhangJ-z, WangD-m, YangG-c, SuZ-m. Journal of Materials Chemistry C, 2014, 2: 2859

This work has been supported by the National Natural Science Foundation of China (Nos.61076066 and 61605105), and the Shaanxi Science & Technology Development Program (No.2011KTCQ01-09).