BF3-assisted insolubilization switching toward bilayer π-conjugated polymer film

Abstract

The fabrication of a bilayer thin film by spin-coating on a π-conjugated polymer film is a crucial step in the processing of organic materials for optoelectronic applications. However, the process is difficult because it depends on a dramatic tuning of the polymer chemical structures used or an irreversible solid-state conversion of the chemical structure. Herein, we report a bilayer π-conjugated polymer film prepared by chemical modification of the polymer, i.e., BF3 coordination-insolubilization by desorption solubilization. Poly[(9,9-dioctylfluorene-2,7-diyl)-alt-(pyridine-2,6-diyl)] (PPF8) is soluble in many organic solvents, but its film became insoluble owing to the BF3 coordination. BF3-assisted insolubilization switching was easily investigated by color (fluorescence) changes. Further film formation on the insoluble film via spin-coating of a head-to-tail poly(3-hexylthiophene) (P3HT) solution produced the bilayer film. The PPF8 was able to remove the BF3 coordination by triethylamine vapor treatment.