Alq3 electron injection

For example, the //V characteristics of devices based on the aluminum chelate complex Alq3, where Ag-Mg or ln-Mg are used as the cathode, can be described by thermionic emission of electrons over the barrier height at the electron injection contact/Alq3 [78]. 

Kido et al. reported using a Li-doped Alq3 layer as a CIM, which generates the radical anions of Alq3 that, in turn, serve as intrinsic electron carriers and lead to improved device performance [57], Lithium salts such as acetate or benzoate can also enhance the electron injection by a similar mechanism [58],... 

Bis(2-(2-hydroxphenyl)benzothiazolate)zinc(II) (Zn(BTZ)2, 85) is an excellent white emitter. The HOMO and LUMO energy levels of Zn(BTZ)2 are —5.41 eV and —2.65 eV, respectively. Just as was found by Zuppiroli et al. for Znq2 derivatives, Zhu et al., found that the electron transport of Zn(BTZ)2 is better than Alq3, though the electron injection barrier is higher for Zn(BTZ)2 [136]. This has been explained by the strong intermolecular interaction of Zn(BTZ)2 molecules. This same group has examined the use of Zn(BTZ)2 as an ETM in PLEDs and the results are consistent with those with SMOLEDs [137]. 

By optimization of device structures and by using different hole and electron injection or transport materials, Chen et al. achieved an excellent red OLED with a very high efficiency based on the DCJTB molecule. The OLED structure is glass (0.7 mm)/SiO2(20 nm) ITO/CFx/NPD(l 10 nm)/Alq3 5% rubrene 2%DCJTB(30 nm)/Alq3(55 nm)/LiF(0.1... 

The criteria for good electron transport materials are that they should transport electrons, block holes, and have a small barrier to electron injection from the metal cathode. The most commonly used ETL in vacuum-deposited OLEDs is tris-(8-hydroxyquinoline) aluminum (Alq3), as shown in Figure 7.7. Alq3 for example, has a LUMO energy level of 3 eV [65] and an electron mobility of 5x 10 5 cm2/(V s) [66]. 

Wang YZ, Qi DC, Chen S, Mao HY, Wee ATS, Gao XY (2010) Tuning the electron injection barrier between Co and Cgo using Alq3 buffer layer. J Appl Phys 108 103719... 

Clearly, Eq. (268) can be approximated by a Poole-Frenkel-type function with a coefficient a > atheor. The exact value of a varies from sample to sample dependent on the type and extent of disorder—through the disorder-dependent component (Ij, Following an example of electron injection from A1 into Alq3 id = 150 nm) (see Fig. 82b), the experimental a values can be calculated from the slopes of the PF-type plots. As predicted by (204) and (265), they should be temperature... 

Figure 105 Electron injection current density vs. average electric field (F U/d) for a Mg/Alq3/Mg sandwich device with a 300 nm— thick Alq film (circles). The dash-dotted line corresponds to a j U2 dependence the dashed line represents a linear plot j U. After Ref. 470. Copyright 2002 American Institute of Physics.

LUMO of Alq3 [30,41]. However, for an actual electron injection process in organic electronic devices, as stated in Section 6.2, Eqj rather than is more appropriate for the estimation of the electron-injection barrier. In Figure 6.7, the two LUMO positions (Elumo-opi arwl lumo) of Alqj are shown with dashed lines for comparison, in which the Elumo was extracted from Ref. [42]. Obviously, the Elumo locates around 1 eV above Ep, which is too high to account for the Fermi level pinning. 

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