Synthesis and characterization of photo-cross-linkable hole-conducting polymers

The synthesis and characterization of side-chain polymers functionalized with hole-transporting units and photo-cross-linkable groups, which can be used for solution-based preparation of multilayer organic light-emitting devices (OLEDs), are discussed. The concept deals with triarylamine and oxetane-functionalized styrenes, which are copolymerized by radical polymerization. Four different types of hole-transporting monomers were combined with one cross-linkable monomer in two different ratios, yielding two groups of each four polymers (P1A...P4A and P1B...P4B). The polymers were investigated by NMR spectroscopy, molecular weights were determined by GPC with light scattering, and the thermal properties were measured with differential scanning calorimetry (DSC). Optical characterization by UV-vis and fluorescence spectroscopy was performed. Electrochemical and cross-linking characteristics of the copolymers were investigated to proove this strategy's potential in application for modern multilayer polymer OLEDs. Finally, hole-only devices were prepared for evaluation of the semiconductive performance of the materials.