Triphenylamine charge transport

Very efficient phosphorescent OLEDs with a D-EML and p- and n-doped charge-transporting layers have been demonstrated. Their device structure is presented in Figure 14.41. The hole-transporting part of the D-EML consists of 4,4 4"-tris(carbazolyl)-triphenylamine (TCTA) doped... 

The hole-transporting layer contains highly electron-rich aromatic compounds, such as the triphenylamine derivative, /n-MDTA, 11.9, whose role is to provide the required charge transport properties (Figure 11.7). Fluorescent dyes with high quantum yields are used to... 

Benefiting from its special propeller starburst molecular structure, amorphous materials with isotropic optical and charge-transporting properties could be expected when combining triphenylamine with linear TZ-conjugated systems. The synthesis is shown in Figure 2.36. 

The transport-active groups can be part of the polymer backbone structure, they can be covalently linked as pendant groups to a vinyl or similar chain such as carbazole groups (substituted aromatic amines) in PVK, or need not be covalently attached to the polymer backbone at all. Indeed, solid solutions of NIPC in polycarbonate display hole mobilities that are comparable to those in PVK [19, 20]. The polymer backbone in PVK does not contribute to transport, but merely ties the transport-active groups together. Similarly, both solid solutions of triphenylamine (TPA) in polycarbonate [21] and poly (methacrylate) with pendant triphenylamine groups [22] display photoconductivity and charge transport. 

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