| Abstract
| - Modification of inorganic electrode surfaces has attracted great attention in the quest to optimize organic optoelectronic devices. An air-stable, cross-linkable trimethoxysilane functionalized hole-transporting triarylamine (4,4′-bis[(p-trimethoxysilylpropylphenyl)phenylamino]biphenyl, TPD−[Si(OMe)3]2) has been synthesized and self-assembled or spin-coated onto tin-doped indium oxide (ITO) anode surfaces to form monolayers or multilayer siloxane films, respectively. The modified ITO surfaces were characterized by advancing aqueous contact angle, X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), and cyclic voltammetry (CV). Increased surface work function and enhanced ITO−hole transport layer (HTL) contact via robust covalent bonding are expected to facilitate hole injection from the ITO anode, resulting in organic light-emitting diode (OLED) performance enhancement versus that of a device without such interlayers. For a device having the structure ITO/spin-coated-TPD−[Si(OMe)3]2 from aqueous alcohol + acetic acid blend solution (40 nm)/NPB (20 nm)/Alq (60 nm)/LiF (1 nm)/Al (100 nm), a maximum light output of 32 800 cd/m2, a 4.25 V turn-on voltage, and a maximum current efficiency of 5.8 cd/A is achieved. This performance is comparable to or superior to that of analogous devices prepared with analogous trichorosilyl precursors. The air-stable interlayer material developed here is also applicable to large-area coating techniques.
- An air-stable, cross-linkable trimethoxysilane functionalized hole-transporting triarylamine (TPD−[Si(OMe)3]2) has been synthesized and self-assembled or spin-coated onto ITO anode surfaces to form monolayers or multilayer siloxane films, respectively. Increased surface work function and enhanced ITO−HTL contact via robust covalent bonding can facilitate hole injection from the ITO anode, resulting in OLED performance enhancement versus that of device without such interlayers.
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