Mobilities electroluminescence devices

Kepler et al. (1995) measured electron and hole mobilities of tris(8-hydroxyquinoline)aluminum (Alq). Alq is of interest for electroluminescent devices. The photocurrent transients for both carriers were highly dispersive. Transit times could be resolved only from double logarithmic transients. The electron mobilities were approximately two orders of magnitude higher than hole mobilities. Figure 46 compares the room temperature electron and hole mobilities. The dashed line represents electron mobilities reported by Hosokawa et al. (1994). At 4 x 105 V/cm, the electron and hole mobilities are 1.4 x 10-6 cm2/Vs and 2.0 x 10-8 cm2 Vs. The activation energy for the electron mobility was reported as 0.56 eV. Later results of Lin et al. (1996) were in excellent agreement with the hole mobilities reported by Kepler et al. 

TAZ, c.f. Figure 9.5, is a low electron mobility material. It can be used as a hole blocking layer, which may limit electron injection and transfer in electroluminescent devices. The triazole unit was found to be an effective r-conjugation interrupter and can play the rigid spacer role in determining the emission color of the resulting copolymer. ... 

Two main methods have been used to measure the charge carrier mobility in electroluminescent polymers time of flight (TOF) carrier transit time measurements and analysis of the current-voltage (1-V) characteristics of single carrier devices in the space charge-limited current (SCLC) regime. A summary of the results for the hole mobility of PPV and PPV-related polymers is given in Table 11-1 [24, 27-32]. For... 

It is well known that solid-state LECs exhibit a significant response time since electroluminescence can only occur after the ionic double-layers have been built up at the electrode interfaces [79,82]. Since in this case only the PFg anion is mobile, the double-layers are formed by accumulation and depletion of PFg at the anode and cathode, respectively. The LEC device with 45 started to emit blue-green light at a bias of 5 V after several minutes. The electroluminescence spectrum, as shown in Fig. 36 (trace a), is very similar to the photoluminescence spectrum recorded for a spin-coated film on glass and of a solution of the complex. For comparison, the electroluminescence... 

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