- Synthesis and characterization of bifunctional materials for electro-optical applications (2005)
- This thesis is dealing basically with synthesis of organic materials for electro-optical applications and interfacial modifications in such applications. It is structured into two major sections each of which presenting a new concept of bifunctional materials: I. Bifunctional Ru(II) dyes carrying hole transport units II. Fully functionalized AB-diblock copolymers I. Bifunctional Ru(II) dyes carrying hole transport units for interface modification in solid-state dye-sensitized nc-Titaniumdioxide solar cells The main concern in this part of this work was the improvement of the Titaniumdioxide/ dye / hole conductor interfaces in solid-state dye-sensitized Titaniumdioxide solar cells. Therefore novel concepts of bifunctional materials carrying light absorbing Ru(II) dye centre as well as hole transport triphenylamine moieties were developed for the following reasons: • Improvement of wetting between polar Ru(II) dye layer and the non-polar spiro-hole conductor. • Spatial separation of excited dye cation centre (HOMO) away from the Titaniumdioxide surface. • Retardation of recombination of holes in the dye molecule with electrons in Titaniumdioxide. In order to reach these goals, novel bipyridine ligands carrying hole transport units (bpy-TPA 6 and bpy-TPD 11) with bipyridine centre for coordination of a transition metal atom have been prepared. In a metallation step a Ru(II) dye was created which carries holetransport moieties as antenna groups. The new, bifunctional materials have been characterized and their potential for application in electro-optical devices have been investigated. II. Fully functionalized AB-diblock copolymers carrying hole transport and NLO-dye blocks Another synthetic approach of this thesis was to explore the suitability of the polymerization technique ATRP for the synthesis of fully functionalized AB-diblock copolymers for photorefractive applications. For this purpose, 4-bromostyrene was polymerized via ATRP using alpha-chloromethylpropionate as initiator and CuCl / PMDETA as catalytic system yielding poly(4-bromostyrene) macroinitiators (19 a – e). The control of this polymerization reaction was verified by GC analysis before the macroinitiators had been used to initiate the polymerization of HEMA-TBDMS which was applied as monomer for the second block. By this method, AB-diblock copolymers have been prepared consisting of a poly(4-bromostyrene) block and a poly(HEMA-TBDMS) block (21). Polymeranalogous reaction yielded the desired fully functionalized block copolymers carrying hole transport and NLO-dye block.