Convenient synthesis and polymerization of 5,6‐disubstituted dithiophthalides toward soluble poly(isothianaphthene): An initial spectroscopic characterization of the resulting low‐band‐gap polymers

Abstract

A new synthetic procedure toward substituted dithiophthalides, 5,6-dialkyloxydithiophthalide and 5,6-dithioalkyldithiophthalide, is presented. 5,6-Dithiooctyldithiophthalide was obtained from 4,5-dichlorophthalic acid in an eight-step reaction with an overall yield of 26%. 5,6-Dioctyloxydithiophthalide was obtained from 4,5dihydroxyphthalic acid dimethyl ester in a seven-step reaction (overall yield ϭ 15%). Both monomers were polymerized by a thermal and nonoxidative polymerization that resulted in soluble poly(isothianaphthene) derivatives with a band gap of about 1.2 eV. Photoinduced absorption measurements revealed the existence of charged excitations upon illumination. The photoinduced charge generation, combined with the extensive light-harvesting properties and the easy processability, makes these materials quite promising for photovoltaic applications.

Plastic Solar Cells Based on Fluorenone-Containing Oligomers and Regioregular Alternate Copolymers

“…These bathochromic shifts can be considered as a spectroscopic manifestation of an increasing planarity and rigidity of the oligothiophene blocks in between the fluorenone subunits which result in a significant enhancement of the p-electron delocalization and, as a consequence, in a decrease of the energy bandgap (E g ) of the monomer and the copolymers. Indeed, E g values of 1.98, 1.93, and 1.52 eV (determined following the method described by Polec et al [23] ) for PDOBTF, TVF, and PTVF, respectively, are fully consistent with this assumption. One should also note that, in the case of PTVF, the visible-absorption spectral lines are broadened and that the band originating from the carbonyl group remains unresolved.…”

Fullerene‐based processable polymers as plausible acceptors in photovoltaic applications

“…In experimental conditions, the oxidation potential ( E ) of ferrocene was 0.06 V versus Ag/Ag + . Thus, LUMO levels can be determined according to the following equation:64 where E is the onset of the first reduction potential of the material versus Ag/Ag + .…”

Quinoidal conjugated polymers with open-shell character

“…Polymer Chemistry have also been reported, such as Grignard metathesis polymerization 43 and nonoxidative polymerization based on phthalidederived monomers. 52,53 Under oxidative conditions (Fig. 4c), the afforded polymers are in the doped state, containing charged quinoidal structures and featuring narrowed bandgaps and enhanced π-conjugation.…”