Molecular self-assembly routes to electroluminescent multilayer structures

Self-limiting siloxane chemisorptive self-assembly approaches have been employed to construct multilayer organic LED (OLED) structures. Extensive characterization of the deposition of a prototype triaryamine hole transport layer precursor on ITO using ellipsometry, X-ray reflectivity, AFM, XPS, and cyclic voltammetry reveal that smooth, contiguous, pinhole-free multilayer structures can be sequentially built up angstrom-level precision. Vapor deposition of a conventional emissive/electron transport layer and a metal electrode on the self-assembled HTL structure yields stable OLED structures with low turn-on voltages, high light output, and good external quantum efficiencies. Finally, self-assembly of an emissive layer on an ITO/HTL structure, followed by a LiF buffer layer and metal electrode, affords the first totally self-assembled two-layer OLED devices which emit continuous blue light.