Tetra-alkoxy substituted PPV derivatives: a new class of highly soluble liquid crystalline conjugated polymers
Two first examples of highly soluble tetra-alkoxy substituted PPV derivatives, poly(2,3,5,6-tetrahexyloxy-1,4-phenylene vinylene) (TH-PPV) and poly[2,3,5,6-tetra(2'-ethyl-hexyloxy)-1,4-phenylene vinylene] TEH-PPV, are presented. Both polymers have been fully characterized and the solubility and UV-Vis absorption characteristics have been studied in various organic solvents. Due to the symmetric nature of the repeating unit, TH-PPV and TEH-PPV have an inherently regioregular nature, which is unusual for PPV-type polymers. Observations from polarized light microscopy and differential scanning calorimetry indicate that TH-PPV exhibits thermally induced order resulting in a liquid crystalline m…
Ester-functionalized poly(3-alkylthiophene) copolymers : synthesis, physicochemical characterization and performance in bulk heterojunction organic solar cells
Abstract The introduction of functional moieties in the donor polymer (side chains) offers a potential pathway toward selective modification of the nanomorphology of conjugated polymer:fullerene active layer blends applied in bulk heterojunction organic photovoltaics, pursuing morphology control and solar cell stability. For this purpose, two types of poly(3-alkylthiophene) random copolymers, incorporating different amounts (10/30/50%) of ester-functionalized side chains, were efficiently synthesized using the Rieke method. The solar cell performance of the functionalized copolymers was evaluated and compared to the pristine P3HT:PCBM system. It was observed that the physicochemical and opt…
Solution-processed bi-layer polythiophene–fullerene organic solar cells
An ionic polymer based on a polythiophene backbone with appended imidazolium moieties was successfully implemented as a donor material in fully solution-processed efficient bi-layer solar cells prepared by the low impact meniscus coating technique. High fill factors and device reproducibility were obtained, even for ultrathin polymer layers, indicating excellent film formation properties and good compatibility with solution processing techniques. The possibility of smooth counter ion exchange, allowing solubility modification and efficiency tuning, enables exploration of new functionalities and other device architectures.