In this work new monomers and polymers with donor-acceptor ability and polymers containing diketopyrrolo[3,2-b]pyrrole (isoDPP), benzodione and naphthodione chromophores in the main chain with deep colour, broad absorption and low band gap are prepared and investigated. The compounds might be suitable for electronic applications, especially in solar cell devices. Characteristic properties are studied using spectroscopic methods (UV/vis, fluorescecne, NMR spectroscopy), gel permeation chromatography, cyclic voltammetry, elemental analysis, X-ray diffraction, differential scanning calorimetry, and thermogravimetric analysis.
Using Stille coupling, conjugated polymers containing isoDPP were prepared. The polymers exhibit a strong bathochromic shift compared with the previously reported isoDPP polymers and also show a high glass transition temperature (Tg) and excellent thermal stability. Photoirradiation studies indicate that the polymers in solution are extremely stable against UV and visible light irradiation. Spectroelectrochemical studies indicated a reversible electrochromism with isosbestic points near 710 nm.
Using Pd-atalysed Buchwald amination, some polymers based on aminobenzodiones were prepared and characterized. The polymers exhibit quite low band gaps (1.07 to 1.18 eV), high photostabilty and a large solvatochromic shift up to 3140 cm–1. Furthermore, the polymers show broad UV/vis absorption bands in a range from 400 to 900 nm with high extinction coefficients of 1.7 to 3.1*104 L mol–1 cm–1.
Furthermore, four new monomers and two polymers based on naphthodifuranone (NDF) were synthesized. These compounds exhibit broad UV/vis absorption bands. Apart from that, for the first time monomers and polymers based on naphthodipyrrolidone (NDP) were synthesized in this work. The NDP-based polymers not only exhibit broad UV/vis absorption with high extinction coefficients, but also possess low band gaps. The broad absorption in the visible, combined with high colour depth and low band gap render NDP-based polymers interesting as building blocks for optoelectronic materials, especially for solar cell applications
