Electron injection and transport for high-performance inverted organic light-emitting diodes

Figures & data

Figure 1. Device structures of the conventional OLED and the iOLED, respectively.

Figure 2. J–V characteristics of electron-only devices depending on the different deposition sequences of a thin LiF interlayer. [Reprinted with permission from Heil et al. 44, © 2001, American Institute of Physics.]

Figure 3. Energy level diagrams of doped organic layers obtained via (a) UPS, (b) KP, and (c) C−V measurements, respectively. [Reprinted from Blochwitz et al. 57, © 2001, with permission from Elsevier; Kröger et al. 73, © 2007 by American Physical Society; and Lee et al. 74, © 2012, Wiley-VCH.]

Figure 4. Change in the energy barrier at the M/O interface by controlling the orientation of the organic material. Energy level diagram for the (a) standing-6T/standing-DH6T/lying-DH6T-monolayer/Ag(111) structure, and (b) ITO/ZnPc/C60 and ITO/CuI/ZnPc/C60. [Reprinted from Duhm et al. 82, © 2008, with permission from Macmillan Publishers, Ltd. and Kim et al. 86, © 2013, with permission from Elsevier.]

Figure 5. Device performances of three different iOLEDs, using the B3PYMPM, Bphen, and TPBi homo-junctions, respectively. (a) Current J–V–L characteristics and (b) quantum efficiency-luminance (η-L) characteristics of the iOLEDs. [Reprinted from Lee et al. 27, © 2011, with permission from Elsevier.]

Table 1. Performances of the iOLEDs, using three different homo-junctions. The operating voltage at injection and turn-on, the EQE at maximum and 1000 cd/m², and the power efficiency at maximum and 1000 cd/m² are listed, respectively. [Reprinted from Lee et al. 27, © 2011, with permission from Elsevier.]

	Operating voltage (V)		EQE (%)		Power Efficiency (lm/W)
Homo-junction	Injection	@ 1 cd/m^2	Max.	@1000 cd/m^2	Max.	@1000 cd/m^2
B3PYMPM	1.9	2.4	19.8	13.5	79.8	33.3
Bphen	2.2	3.6	14.2	13.6	37.3	27.2
TPBi	2.4	4.0	17.1	14.3	42.7	21.2

Figure 6. J–V characteristics of electron-only devices with inverted structures of (a) ITO/Rb₂CO₃-doped ETL (50 m, 15 wt%)/Al (open symbol) or (b) ITO/Rb₂CO₃-doped ETL (20 m, 15 wt%)/undoped ETL (30 nm)/Al (solid symbol). [Reprinted from Lee et al. 27, © 2011, with permission from Elsevier.]

Figure 7. Energy level diagrams of (a) ITO/n-B3PYMPM/ B3PYMPM, (b) ITO/n-Bphen/Bphen, and (c) ITO/n-TPBi/ TPBi, respectively, obtained via UPS measurement. [Reprinted from Lee et al. 27, © 2011, with permission from Elsevier.]

Figure 8. Device structures of three different iOLEDs with the B3PYMPM homo-junction, n-B3PYMPM/Bphen hetero-junction, and n-B3PYMPM/TPBi hetero-junction, respectively.

Figure 9. Device performances of three different iOLEDs with the n-B3PYMPM/B3PYMPM homo-junction, n-B3PYMPM/Bphen hetero-junction, and n-B3PYMPM/TPBi hetero-junction as the ETL, respectively. (a) J–V–L and (b) η-L characteristics of the iOLEDs.

Figure 10. Device structure of the iOLED using the organic p–n junction as an electron injection and electron-transporting layer, and J–V characteristics of the organic p–n junction composed of p-CuPc/n-Bphen. [Reprinted from Lee et al. 116, © 2012, with permission from Elsevier.]

Figure 11. Device performances of five different iOLEDs depending on the work function of the bottom cathode. (a) J–V and (b) current density–luminance (L−V) characteristics of the iOLEDs, and the value of the work function of the bottom cathode therein. [Reprinted from Lee et al. 116, © 2012, with permission from Elsevier.]

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