Low Molecular Weight Materials: Electron-Transport Materials

  • Hisahiro SasabeEmail author
  • Junji Kido
Living reference work entry


Since the first report of practical OLED by Tang and VanSlyke in 1987, metal complex, 8-hydroxyquinoline aluminum (Alq) is widely used for fluorescent OLEDs. However, Alq cannot be used in second- and third-generation green and blue OLEDs due to its low triplet energy (ET) of 2.15 eV. Therefore, researchers have been exploring a novel ETM with high ET in this decade. In this chapter, we summarized and demonstrated representative wide-energy-gap ETMs for use in second- and third-generation OLEDs, and some typical strategies for high-performance ETMs are demonstrated. Further, future challenges are briefly discussed.


Electron-transport material Wide-energy gap Low-operating-voltage Electron mobility Molecular orientation Weak hydrogen bond 


  1. Aizawa N, Pu YJ, Watanabe M, Chiba T, Ideta K, Toyota N, Igarashi M, Suzuri Y, Sasabe H, Kido J (2014) Solution-processed multilayer small-molecule light-emitting devices with high-efficiency white-light emission. Nat Commun 5:5756CrossRefGoogle Scholar
  2. Chen D, Su S-J, Cao Y (2014) Nitrogen heterocycle-containing materials for highly efficient phosphorescent OLEDs with low operating voltage. J Mater Chem C 2:9565–9578ADSCrossRefGoogle Scholar
  3. Hughes G, Bryce MR (2005) Electron-transporting materials for organic electroluminescent and electrophosphorescent devices. J Mater Chem 15:94–107CrossRefGoogle Scholar
  4. Hung WY, Fang GC, Lin SW, Cheng SH, Wong KT, Kuo TY, Chou PT (2014) The first tandem, all-exciplex-based WOLED. Sci Rep 4:5161CrossRefGoogle Scholar
  5. Ichikawa M, Kawaguchi T, Kobayashi K, Miki T, Furukawa K, Koyama T, Taniguchi Y (2006) Bipyridyl oxadiazoles as efficient and durable electron-transporting and hole-blocking molecular materials. J Mater Chem 16:221–225CrossRefGoogle Scholar
  6. Ichikawa M, Hiramatsu N, Yokoyama N, Miki T, Narita S, Koyama T, Taniguchi Y (2007) Electron transport with mobility above 10–3 cm2/Vs in amorphous film of co-planar bipyridyl-substituted oxadiazole. Phys Status Solidi (RRL) Rapid Res Lett 1:R37–R39ADSCrossRefGoogle Scholar
  7. Ichikawa M, Yamamoto T, Jeon H-G, Kase K, Hayashi S, Nagaoka M, Yokoyama N (2012) Benzene substituted with bipyridine and terpyridine as electron-transporting materials for organic light-emitting devices. J Mater Chem 22:6765–6773CrossRefGoogle Scholar
  8. Kim BS, Lee JY (2014) Engineering of mixed host for high external quantum efficiency above 25% in green thermally activated delayed fluorescence device. Adv Funct Mater 24:3970–3977CrossRefGoogle Scholar
  9. Kulkarni AP, Tonzola CJ, Babel A, Jenekhe SA (2004) Electron transport materials for organic light-emitting diodes. Chem Mater 16:4556–4573CrossRefGoogle Scholar
  10. Lee J-H, Cheng S-H, Yoo S-J, Shin H, Chang J-H, Wu C-I, Wong K-T, Kim J-J (2015) An exciplex forming host for highly efficient blue organic light emitting diodes with low driving voltage. Adv Funct Mater 25:361–366CrossRefGoogle Scholar
  11. Montes VA, Perez-Bolivar C, Estrada LA, Shinar J, Anzenbacher P (2007) Ultrafast dynamics of triplet excitons in Alq(3)-bridge-Pt(II)porphyrin electroluminescent materials. J Am Chem Soc 129:12598–12599CrossRefGoogle Scholar
  12. Sasabe H, Kido J (2011) Multifunctional materials in high-performance OLEDs: challenges for solid-state lighting. Chem Mater 23:621–630CrossRefGoogle Scholar
  13. Sasabe H, Kido J (2013a) Recent progress in phosphorescent organic light-emitting devices. Eur J Org Chem 2013:7653–7663CrossRefGoogle Scholar
  14. Sasabe H, Kido J (2013b) Development of high performance OLEDs for general lighting. J Mater Chem C 1:1699–1707CrossRefGoogle Scholar
  15. Sasabe H, Gonmori E, Chiba T, Li YJ, Tanaka D, Su SJ, Takeda T, Pu YJ, Nakayama KI, Kido J (2008a) Wide-energy-gap electron-transport materials containing 3,5-dipyridylphenyl moieties for an ultra high efficiency blue organic light-emitting device. Chem Mater 20:5951–5953CrossRefGoogle Scholar
  16. Sasabe H, Chiba T, Su SJ, Pu YJ, Nakayama K, Kido J (2008b) 2-Phenylpyrimidine skeleton-based electron-transport materials for extremely efficient green organic light-emitting devices. Chem Commun (Camb) (44):5821–5823Google Scholar
  17. Sasabe H, Tanaka D, Yokoyama D, Chiba T, Pu Y-J, Nakayama K-I, Yokoyama M, Kido J (2011) Influence of substituted pyridine rings on physical properties and electron mobilities of 2-methylpyrimidine skeleton-based electron transporters. Adv Funct Mater 21:336–342CrossRefGoogle Scholar
  18. Sasabe H, Nakanishi H, Watanabe Y, Yano S, Hirasawa M, Pu Y-J, Kido J (2013) Extremely low operating voltage green phosphorescent organic light-emitting devices. Adv Funct Mater 23:5550–5555CrossRefGoogle Scholar
  19. Su S-J, Chiba T, Takeda T, Kido J (2008) Pyridine-containing triphenylbenzene derivatives with high electron mobility for highly efficient phosphorescent OLEDs. Adv Mater 20:2125–2130CrossRefGoogle Scholar
  20. Su SJ, Sasabe H, Pu YJ, Nakayama K, Kido J (2010) Tuning energy levels of electron-transport materials by nitrogen orientation for electrophosphorescent devices with an ‘Ideal’ operating voltage. Adv Mater 22:3311–3316CrossRefGoogle Scholar
  21. Sun C, Hudson ZM, Helander MG, Lu ZH, Wang SN (2011) A polyboryl-functionalized triazine as an electron transport material for OLEDs. Organometallics 30:5552–5555CrossRefGoogle Scholar
  22. Tanaka D, Sasabe H, Li Y-J, Su S-J, Takeda T, Kido J (2007) Ultra high efficiency green organic light-emitting devices. Jpn J Appl Phys 46:L10–L12CrossRefGoogle Scholar
  23. Tang CW, VanSlyke SA (1987) Organic electroluminescent diodes. Appl Phys Lett 51:913–915ADSCrossRefGoogle Scholar
  24. Von Ruden AL, Cosimbescu L, Polikarpov E, Koech PK, Swensen JS, Wang L, Darsell JT, Padmaperuma AB (2010) Phosphine oxide based electron transporting and hole blocking materials for blue electrophosphorescent organic light emitting devices. Chem Mater 22:5678–5686CrossRefGoogle Scholar
  25. Watanabe Y, Sasabe H, Yokoyama D, Beppu T, Katagiri H, Pu Y-J, Kido J (2015) Simultaneous manipulation of intramolecular and intermolecular hydrogen bonds in n-type organic semiconductor layers: realization of horizontal orientation in OLEDs. Adv Opt Mater 3:769–773CrossRefGoogle Scholar
  26. Xiao L, Su S-J, Agata Y, Lan H, Kido J (2009) Nearly 100% internal quantum efficiency in an organic blue-light electrophosphorescent device using a weak electron transporting material with a wide energy gap. Adv Mater 21:1271–1274CrossRefGoogle Scholar
  27. Xiao L, Chen Z, Qu B, Luo J, Kong S, Gong Q, Kido J (2011) Recent progresses on materials for electrophosphorescent organic light-emitting devices. Adv Mater 23:926–952CrossRefGoogle Scholar
  28. Yokoyama D, Sakaguchi A, Suzuki M, Adachi C (2009) Enhancement of electron transport by horizontal molecular orientation of oxadiazole planar molecules in organic amorphous films. Appl Phys Lett 95:243303ADSCrossRefGoogle Scholar
  29. Yokoyama D, Sasabe H, Furukawa Y, Adachi C, Kido J (2011) Molecular stacking induced by intermolecular C-H···N hydrogen bonds leading to high carrier mobility in vacuum-deposited organic films. Adv Funct Mater 21:1375–1382CrossRefGoogle Scholar
  30. Yook KS, Lee JY (2012) Organic materials for deep blue phosphorescent organic light-emitting diodes. Adv Mater 24:3169–3190CrossRefGoogle Scholar
  31. Zhang Q, Li B, Huang S, Nomura H, Tanaka H, Adachi C (2014) Efficient blue organic light-emitting diodes employing thermally activated delayed fluorescence. Nat Photonics 8:326–332ADSCrossRefGoogle Scholar

Copyright information

© Springer Japan KK, part of Springer Nature 2019

Authors and Affiliations

  1. 1.Department of Organic Device EngineeringYamagata UniversityYonezawaJapan
  2. 2.Graduate School of Organic Materials Science, Research Center for Organic ElectronicsYamagata UniversityYamagataJapan

Section editors and affiliations

  • Hironori Kaji
    • 1
  1. 1.Division of Environmental Chemistry, Institute for Chemical ResearchKyoto UniversityKyotoJapan

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