Electrical doping

The rates (23) and (24) depend on the electrical doping through (eD - eF), as well as on the temperature, which affects the r s and the Z s. Fig. 2(a) shows the dependence on (eD - eF). Note that the knee, which occurs when the two terms on the right of (23) or (24) are equal, comes at the same abscissa for the r+0 curve as for the r0+ curve, and that the ratio r0+/r+0—whose logarithm is the difference of the two ordinates—would plot to a straight line on the logarithmic scale. This latter fact is just an expression of the equilibrium relation (3), since in a steady state we must have... 

Walzer K, Maennig B, Pfeiffer M, Leo K (2007) Highly efficient organic devices based on electrically doped transport layers. Chem Rev 107 1233... 

Lee J-H, Leem D-S, Kim J-J (2010) Effect of host organic semiconductors on electrical doping. Org Electron 11 486... 

Fehse K, Olthof S, Walzer K, Leo K, Johnson RL, Glowatzki H, Broker B, Koch N (2007) Energy level alignment of electrically doped hole transport layers with transparent and conductive indium tin oxide and polymer anodes. J Appl Phys 102 073719... 

Monomer 44a was also found to electropolymerize on indium-tin-oxide (ITO) under potential-sweep conditions (Figure 33). The resulting film poly-44a) can be electrically doped by oxidation, as was demonstrated by UV/Vis spectroelectrochem-istry (oxidative dotation leads to a broad absorption band beyond 1000 nm). We found that on irradiation with a 500 W incandescent lamp the pristine film (at 0 mV vs. Ag/AgCl) gave rise to the formation of the VHF form poly-44b). Under thermal conditions, the DHA spectrum could be restored (Figure 34). 

We fabricated a much more sophisticated device using compound 3 (Mariano et al., 2009) and, to check the limit in brightness and stability of the compound, we realized an OLED based on electrically doped transport layers, i.e. in the so-called p-i-n (p-type-intrinsic-n-type) configuration (Walzer et al., 2007). 

Further, introduction of new technological concepts like electrical doping of transport layers has enhanced the OLED efficiency to more than 100 Im/W and enhanced life time of the devices to more than 100,000 hours which is better than the gas filled discharge lamps (Murano et al 2005). However, efficiency and lifetime are still considered widely as the big obstacles on the road of OLED development. A further impa-ovement in the OLED performance relies on the more detailed xmderstanding of the EL physics and the new development in the OLED materials, structure and fabrication. 

Schematic structure of p-i-n red phosphorescent OLED with electrically doped chargetransporting layers.

Energy levels and layer structures of the red p-i-n OLEDs with various materials in the HBL and electrically doped transport layers. Indicator layer (ITL) was used as optional interlayer, which served only as sensor for exciton distribution. (From Meerheim, R. et al., /. Appl. Phys., 104,0145510,2008. With permission.)... 

Schematic structure of a phosphorescent OLED with double emission EML and electrically doped charge-transporting layers.

J.E. Cochran, M.J.N. Junk, A.M. GlaudeU, P.L. Miller, J.S. Cowart, M.F. Toney, CJ. Hawker, B.F. Chmelka, M.L. Chabinyc, Molecular interactions and ordering in electrically doped polymers blends of PBTTT and F4TCNQ, Macromolecides... 

Polymers have been employed in many fields where their applications range from common daily use to sophisticated aerospace applications. They are primarily used for insulators in the electrical and electronic industries. Recently, however, conjugated unsaturated systems have received special attraction due to their ability to conduct electricity. Doped polyacetylene, the first well characterized and studied conducting polymer, possesses conductivities as high as 10 S/cm.l Such values are comparable to metal conductors. 

Ion implantation The physical injection of high energy (MeV) ions into the surface region of a material to change the electrical (Doping) or mechanical properties of the near-surface region. 

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