Novel Aromatic Amines for Photoconductor and Organic Electronic Applications

Abstract

Aromatic amines are frequently used as hole conductors in copiers and laser printers. In the last decade there has been increasing interest to extend the use of aromatic amines to organic light emitting diodes (OLEDs) as well as to organic field-effect transistors (OFETs) developed for printable organic electronics. In this contribution star-shaped aromatic amines which form stable amorphous phases are introduced. Such materials are often called molecular glasses. We have used molecular glasses with triphenylamine, triphenylbenzene and fluorene units as blue emitters and hole blocking materials in OLEDs. The layer thickness of the hole transport and emission layer and the hole blocking layer were optimized in a combinatorial approach which leads to pure blue emitting OLEDs with color coordinates of x=0.15 / y=0.15, a brightness of 400 cd/m2 and an efficiency of 2 cd/A. We have also used molecular glasses with triphenylamine and carbazole units as organic semiconductors in OFETs and obtained environmentally stable transistors with mobilities up to 10−4 cm2/Vs.